Easy add-on Projects for Spectrum ZX81 & ACE (Redux): Forward

There was a time when plugging a home fabricated electronics project into, onto or out the back of a Computer was an actively encouraged pursuit. Hardware project books for many a micro computer filled bookstore shelves which intern were filled with many a hardware DIY add-on. Easy add-on Projects for the Spectrum ZX81 and Ace, was one such tome of 80s knowledge, and it's been taking filling space on book self for a couple of years.

Easy add-on Projects for the Spectrum, a good read with some fun possibilities 

In order to undertake the builds presented within Easy add-on Projects for the Spectrum ZX81 and Ace, an initially requirement is the construction of an Address Decoder board, itself obviously already an project. In the true maker spirit of the times this involves producing your own PCB. There was at one point an order-able companion board, leasoning the difficulties any period 80's enthusiast lacking in manufacturing resources would face, though notably you still had to populate the PCB with components yourself.

The (non-Address Board Creation) projects themselves are quite an interesting selection, ranging from a primitive scanner, a light pen, a lap counter and to the major project a weather station. Not surprisingly they all have a very 'you could do this with an Arduino or Raspberry Pi' feel to them. In considering this vibe, it could also be a fun aside to implement the same on either of those modern devices, or the other way around by bringing some Arduino projects to the ZX81.

Lets not get to ahead of ourselves, the first order of business is to get down to that Decoder. There are 2 versions of the board presented in the book, one for the Jupiter Ace and one that's compatible with both the ZX81 and Spectrum, it's this board I'll be constructing. There is not a great deal to it, just a few 74 series ICs and other easy-ish to source parts. This is one of the wonderful thing about retro stuff I guess, it's all still relatively easy to source and understand. I'm not going to use the board quite as designed, I'm intending to use SMD components for example to modernise construction, in general however there should be no functional changes.

So, over the course of the coming weeks I'll get down redesigning the Decoder Board and form there onto the actual projects. If you playing along at home the book ' Easy add-on Projects for the Spectrum ZX81 and Ace' is available from the Jupiter Ace Resource Archive. A site well worth an explore given the Ace's close links to the ZX81 and ZX Spectrum.

See more entries for this project: Forward, Part 1, Part 2, Part 3

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Amstrad NC 100, Don't Blow a Fuse

In the last few days I took delivery of an Amstrad NC 100 notepad computer that had been listed on everybodys favourite auction site as not working. The purchase was an educated gamble as all my prior research on the NC 100, along with helpful advice from the Twitter Sphere, pointed to the major cause of failure for these devices being an easy fix. A simple blown fuse that would probably require replacing or circumventing.

After taking the NC 100 apart, locating the fuse where it should be, in the bottom left corner of the main board (power socket facing towards you), I ran a continuity test, the resulting in our prospective blown fuse scenario proving correct.

Amstrad NC 100 Main Board, Left: A Dusty and Blown Fuse. Right: A Temporary Jumper Wire Fix

The non-working Fuse is a  PCB Leaded, 500 mA, 250 V component, which I didn't have to hand. So in order to power up the computer I simply removed the fuse and soldered in a copper jumper wire as a temporary fix. (Next time I place a general component order I'll obtain a new fuse.) This is fine, just as long as I insure the polarity of any power supply is correct, Tip / Outer positive, inner negative.

Interestingly, based on the type of fuse I found in my NC 100 , there seem to be a couple of revisions of the NC 100 board. A number of online references indicate that the fuse should be an SMD component, not a though hole type one. 

A Now Fully Functional Amstrad NC 100

To test, I reconnected the main board to the LCD panel, and screen came to life with a Friendly 'Lithium battery is low' warning, not unexpected as there was no backup battery in the device at the time. Fix completed, and case reassembled, and I'm now the proud owner of a rock bottom priced Amstrad NC 100.

Now to find something for this little notepad computer do, maybe I'll take it to the office and garner some curious and possibly concerning looks at meetings.

Further Viewing

For an entertaining and informative overview of the NC 100, including the replacement of (in this case an SMD) fuse, head over to YouTube and the EEVblog

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The UDG For ZXpand Add-on for the ZX81: Part 1

One of most noticeable graphic element lacking from a ZX81 is perhaps the ability to define said graphic elements. Enter the UDG for ZXpand from Andy Rea, an expansion module available from around mid 2017 that affords the ZX81 owner the opportunity to create User Defined Graphics.

The UDG for ZXpand Hardware

The UDG for ZXpand is designed to be used in conjunction with memory expansions supporting the WRX extensions / modifications. Modern memory boards such as the ZXpand(+) and the ZXblast support this natively. Note that if using period RAM expansions such as the 16k Sinclair RAM pack or one from Memotech, then hardware alterations are required.

The UDG 4 ZXpand Expansion Board.

For an expansion board the UDG 4 ZXpand is quite small, being the width of the ZX81 expansion bus and approximately as deep again.. The expansion is designed to slot horizontally and directly into the ZX81 expansion port, and to be sandwiched  between a ZX81 and supporting RAM Pack / ZXpand / ZXblast.

Configuring the UDG 4 ZXpand for use with available software is a simple matter of adjusting a jumper setting on the board. A small toggle switch might have been a better choice, still one could easily be added by the end user. The jumper can be set 3 ways:

1. Open: No effect, ZX81 operates as normal
2. 64 Mode: Sets the UDGs to a defined limit of 64 Characters. A further 64 characters will be inverse versions.
3. 128 Mode: All available ZX81 characters can be redefined and made available.

Modes 3 in particular provides scope for a complete overhaul of the ZX81s character set. Need some lower case characters, then replace the otherwise seldom used inverse set with something more useful. I'll cover the creation of character sets and the importation of existing fonts in a second post / article.

It's also worth noting that the UDG 4 ZXpand is supported by the 1.8 release of the EightyOne Sinclair Emulator.

Upadated UDG Gamming Goodness

The ability to redefine all 128 character tiles provides the scope for all existing ZX81 games to be retrofitted with HiRes character graphics. A good case in point would be Quicksilvas Galaxians, originally published in 1983 and written by T. Beckworth

A fast paced arcade game, Galaxians exemplifies just what a standard ZX81 can deliver when asked nicely. With the addition of some well done UDGs Galaxians is elevated to a whole new level, the game rivalling the best early games the ZX Spectrum has to offer.

Galaxians Clone with and without UDGs enabled

You can grab the updated version of Galaxians Thanks to Moggy on the Sinclair World Forums. Be sure to search for other updated tittles while there.

The results of redefined character sets on old games depend largely on the quality of the original, or simply revolve around just how the pre-existing Sinclair character set may or may not have have been used. Even in the otherwise brilliantly updated Galaxians there are some oddities to be seen due to this specific limitation. This is most apparent in the Hi Score tables where an "*" character, normally used in game as a player bullet, leads a certain illegibility the player score listing.

New Game Realses

Zedragon version 1, running on a ZX81

Updates to older games is all well and good, but endowing a ZX81 with near ZX Spectrum like powers (minus to colours) the UDG for ZXpand stands to have major impacts on many a new games releases.

There are effectively no limitations plaguing new tittles , these having the potential to provide complex experiences with a full usage of UDGs.

The first of brand new title being Ze dragon, a game so professional it's hard to believe a ZX81 is running behind it. A clone of Atari Sea Dragon, Ze Dragon is a Scramble like game replacing other worldly action with a Submariner adventure.

Ze Dragon was released in late 2017, and February 2018 has seen it updates to Ze Dragon II. The new version features pixel level scrolling, something not before seen in a ZX81 game. (Perhaps some parallax scrolling in version 3?).

Ze Dragon is an impressive conversion, demonstrating the full capabilities of the ZX81, UDG for ZXpand and the ZXpand(+). Perhaps this is not so surprising as the creators behind the both the UDG 4 ZXpand and ZXpand are behind the game. Game Author Sir Morris (Charlie Robson of ZXpand fame), Andy Rea and other co-mariners should be justly proud.

As with Galaxians, Ze Dragon 2 is available over at the Sinclair World Forums.

Ze Dragon 2 running on the EightyOne Sinclair Emulator

Next Time

Well that's a basic review and some games covered, so what about using Andy Reas' clever little device to do our our own bidding. Next post I'll attempt to cover some basics on generating our own UDGs for own games and programs. Covering some simple coding, then moving quickly onto some software that's already available to take all the hard work out of generating new ZX81 characters sets.

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Mystic BBSing with WiModem232s Zeddynets and Pi

Or Networking Disperate Retro Computers?

I've been meaning to write something about the ZX81 Ethernet adapter Zeddynet for a while now, but hadn't got around to it for various reasons. In the last week or so another more general purpose retro network device in the form of a Serial to WiFi modem / network adapter, the WiModem232 crossed my threshold rekindling ideas around networking old computers.

Now we have the basis for a slightly confused and conjoined blog post, one that ends up being not quite a review, mostly not a tutorial and a slightly random collection of ideas on network hardware and software, in which I get a number of ancient machines on-line connected to a BBS, a BBS that ends up being my own local BBS.

Some Networking Hardware Required

Now for a brief look into the networking devices I'm using. Both interfaces are specific to my needs (and small retro collection), the WiModem232 is certainly of much use to the general retro community, where as the Zeddynet is obviously of more limited one machine appeal.

Zeddynet - for a ZX81

Starting with Zeddynet and the ZX81: The Zeddynet board mounts onto a ZX81XT extender / extension board, and combined plugs into the ZX81s expansion bus. The card is quite tall with the Ethernet port located at the top. This arrangement is a little cumbersome, particularly once a network cable is plugged as the cable and the card tend to get in the way of a low-ish sitting desktop monitor. Still we're about to plug a ZX81 into a network, a few aesthetics issues and minor viewing discomforts are hardly of major issue compared to the achievements realised.

Zeddynet Interface

Available sporadically from and designed by the German ZX-Team, Zeddynet as the name implies connects a humble ZX81 to a TCP/IP network via Ethernet cable. Zeddynets first appeared back in 2012, I procured mine mid 2017, unfortunately no more have been produced since then (at the time of writing). Still, keep an eye out on SinclairWorld forums should you desire a fully assembled Zeddynet.

In order to configure and use the Zeddynet expansion on the ZX81 some software is required. At minimum in order  to get a ZX81 connected to online BBSs software in the form of ipconfig and telnet are required. Telneting is only one small part, there are web-browsers and network file managers and more. The German Sinclair forum.tlienhard.com has links to all software and sources.

WiModem232 for Anything with a Serial Port

Around the middle of 2017 Paul Rickards released the WiFi232 Internet Hayes Modem for retro computers, the perfect solution for networking old computers. Sadly the device has remained sold out for months, and may now be permanently unavailable. Luckily and possibly inspired by the original WiFi232, two new solutions have recently hit the market from CBMStuff, the WiModem232 and WiModem232 w/OLED.

WiModem232 w/OLED display

Functionality wise, the only real difference between the WiModem232 and WiModem232 w/OLED is the rather obvious OLED screen. The choice of adapter comes down to a desire for a handy information display or a need for the milliamp power savings brought about by not including it. Note that on both variants an RGB LED provides a status indication allowing you to easily live without the OLED screen.

The modem is configured and connected to a WiFi network by Hayes Modem command extensions. Similarly Hayes commands are used to connect to telnet instances on a local network or further a field.

In order to use the WiModem232 simple terminal software is required. The machines I've tested the WiModem232 with (TRS-80 model 100/102 and an NEC PC-8401) have terminal software built into their ROMs, in all cases this worked perfectly.

BBSs Are Out There

Dial up BBSs were a major thing before the Internet age, but sadly faded into slight irrelevance in the late 90s, but now they're back and on the Internet. In fact there is a whole new (old) world out there waiting to be connected.

Perhaps the best resource for finding BBSs is the Telnet BBS Guide. Telneting to any of the BBSs listed from a modern PC is fairly trivial, being able to telnet from a vintage micro computer is (whoo hoo) exciting.

Testing Interfaces a DIY BBS

Despite the wealth of BBS out there, I wanted to try out Zeddynet and the WiModem232 on my micros' without burdening the various online resources. Possibly I'd rather like keep the BBS running, with a view to opening it up for others to log on at some point. For these reasons I decided to to deploy a Raspberry PI and install some BBS software.

The Telnet BBS Guide helpfully lists the software being used by various BBSs in it's site registry. Of the software listed 'Mystic' BBS seems by far the most popular and actively maintained kit going, plus it has Raspberry Pi versions available that work on all network enabled Pies. A logical choice then.

The setting up 'Mystic' is as easy as unzipping, running a minimal installation, and then starting a BBS server. In less than five minutes you can have a bare bones BBS up and running and telnet-able into. After that 'your mission, should you choose to except it', exposes a whole rabbit hole of configurations and text files to modify in order to tailor and craft a unique BBS experience.

Crafting An 8 Bit Mystic Experience

In its default state Mystic targets computers with 80 columns and full ASCII / ANSI support. This is great for Amigas, Atari STs and IBM clones, not so great for 8 bits micros. This situation is fixable, but it does require a full redesign of the built in theme. The task is not difficult, it does though require some dedication.

All BBS layout files can be altered with tools built into Mystic, thus allowing for complete customisation of a BBSs look and feel. It is even possible to create ASCII and ANSI versions of pages servicing general fallback requirements. As a general design rule in targeting older 8bit machines I found it wise to limit charter selection to the first 128 ASCII characters. Using above this limit you start running into compatibility issues between the various proprietary character sets employed by 80s micros. I'm going out on a limb here and suggesting that period telnet / dial up software should automatically transpose any basic character set incompatibilities if working within the 128 limitation.

Locally Connected

There is a long way to go and to start I've only scratched the service of setting up a BBS and using the Zeddynet and the WiModem232 interfaces. On the BBS side of things my only real attempt at customisation has been the Welcome Screens. For now though it serves as a proof of usability both software and hardware.

LINUX Console

Limiting the choice of characters, but allowing for ANSI colours, a LINUX logon to the ZX-AD BBS (as I've named it) looks plain as opposed to what is possible for a full ANSI/ASCII experience. It does help provide a similar experience across all platforms however.

LINUX Console Connected to the Mystic BBS Software Running Locally on a Raspberry Pi

Sinclair ZX81 with Zeddynet 

I limited the welcome screens width to 64 characters, this fits nicely with ZX81 hires modes (additional hardware required). I'd also created a ANSI and ASCII versions of the welcome screen the ZX81 is using the ASCII variant.

ZX81 with Zeddynet Connected to Local Mystic / ZX-AD BBS

Tandy TRS-80 Model 100 & 102 with WiModem232

The Tandy machines are limted to 40 character width screens. Mystic can support this, but I haven't tailored the welcome screen to the 40 character limit, and the screen therefor doubles around.

Using the Tandy machines I found that the WiModem232 baud rate could also be no higher than 1200 else I started experiencing character loss.

TRS-80 Model 102 Connected to Mystic, 40 columns is Problem at this Stage

NEC-PC8401 with WiModem232

Mystic attempts to verify if a connecting computer supports the ANSI standard, interestingly the NEC-PC8401 reports back that it does. This is of course a lie, as it does not. Regardless of this untruth it will render the display correctly if the first 128 ASCII characters limit is adhered to. Also as fully functional CP/M computer the PC8401 has a 80 column display, consequently there is no issue with screen width, screen length however may pose its own problems latter.

NEC-PC8401 Connected to Local Mystic / ZX-AD BBS

To Summarise

Thus ends a rather scattered post on networking 8bit machines and BBS software. On the hardware side of things I can uttery recommend the WiModem232, it really is very simple to use. Zeddynet is similarly fun in execution. In both cases the full possibilities have hardly been touched on by this post.

As for the running a BBS, it's entirely likely I'll refine and open my local experience up to the broader world. Coming Soon - ZX-AD BBS.

Addendum

In the total absence of ZX-AB BBS, being that it's confined to my local network for the moment, and if you're hankering for a Sinclair related BBS that's online right now, then you can't go past sinclair-retro-bbs:

• Telnet: retrobbs.sinclair.homepc.it Port: 23

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The Sinclair ZX–Micro Computer: System Variables Comparison Chart

Sometimes when you've written an application for the ZX81 or ZX Spectrum you wish to port it to the other, or even back to the ZX80. Sometimes you've used a system variables and you need an easy reference chart to look up correct system address on the target system and move on. But you say, there is no chart, or there was no chart until now.

I got tired of looking through the manuals every time I need to check some System Variable values and decided to just put them all in a chart. Hopefully you might find it similarly useful. A PNG graphic is available below, and if preferred a PDF version can be downloaded.

If anybody notices some glaring or even slightly disturbing error, let me know and I get them ironed out and fixed up.

One final thought, It's quite interesting to see just how many changes were made to the ZX line of computers in the space of 3 or 4 years. There are the obvious physical differences of course, then there are changes witnessed in the System Variables above.

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RetroChallenge 2017/10: Part 8

Keyboards Down on the NEC PC-8401 Challenge.

Sadly it's time to put the keyboard away on the RetroChallenge for October, but not before a quick summary. And did I mention the keyboard yet, it would be remiss to not to.

The PC-8401 has a truly wonderful keyboard, seriously it's a beauty. It seems that particular computer I ended up with has seen very minimal usage. The Alps SKFL series switches are in a fantastic condition, there is no grainy or worn out feel you'd associate with a 40 year old board. The keys themselves are double shot and feel very firm to type on. It would be nice if you could such a keyboard on a laptop today.

Some Closing Thoughts

I think I got to know the PC-PC8401 quite well over the past months activities, with the device proving to be quite a sturdy piece of kit and generally fun to work with. I've still got some more to do though, the big one being the scanning of the remaining manuals for the Internet archive.

Way back at the start I looked what the reviewers has to say on the NEC-PC8401, the major take away criticism being the neglect-ion to include BASIC in ROM. After playing around with the computer over the past month, that point is still a valid one, and hampers the retro usability of the machine, mostly due to memory constraints of adding BASIC to RAM.

Regardless of the above minor issue, the PC-8401 is a fun little device and it'll continue to sit on my desk and or lap for a while to come. I'm looking forward to finding some good uses for it outside the time constraints of the RetroChallenge and I'm certainly going to plan some future projects around it the  PC-840.

That's it for RetroChallange 2017/10, thanks to all involved and particularly to all the other projects, it maks very varied and fun experiance. Now it's back to our regular non-programed blogging experience.

See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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RetroChallenge 2017/10: Part 7

Developing Software on the NEC PC-8401?

Just a bit of fun for this entry. After experimenting with some software development last post, it quickly became apparent that writing software directly on the PC-8401 is a little inconvenient (at least without a memory expansion). This lead to the use of Z88dk for external development and a little cross-compiling to CPM to suite our purposes.

I couldn't help thinking that although the outcome was successful, it seemed a little like cheating. So lets cheat a tiny bit less.

As we know, the PC-8401 comes with a very capable Vt100 compatible Terminal program, one that's perfect for interfacing with LINUX. Now with minimal imagination required  lets pretend it's 1985 and we're developing on some extremely expensive time sharing remote platform tended by white coat wearing professionals.

There are many ways to configure serial / rs232 terminal sessions within LINIX, so here's one way, and one that's really simple although not a permanent on boot ready option.

First, we need to find the correct Serial Port. I'm using a USB to serial adaptor and need to know which exact device to target.

From the command line in LINUX issue: dmesg | grep USB

This yields a load of messages, but I'm looking for something as below.

[   22.444199] usbserial: USB Serial support registered for pl2303
[   22.444774] usb 1-10: pl2303 converter now attached to ttyUSB1

Now knowing knowing which USB device is the serial converter, it's an easy matter to setup a terminal console.

sudo stty -F /dev/ttyUSB1 cols 80 rows 15 1200
TERM=vt100 ksh </dev/ttyUSB1 > /dev/ttyUSB1 2>&1 &

Once that's all done, I can start up the PC-8401s Terminal program, configure it to 1200 baud 1 stop bit, no parity and 8 bit word length and I'm up and running a LINUX remote console. From there it's time to start up a text editor, VI, Emacs or Nano and get developing.

NEC-PC8401 with and open LINUX console running nano and editing code

Once some very impressive software has been developed, it'll need to be transferred to the PC-8401 to be executed in all it's glory, and LINUX provides a couple of easy to use xmodem commands to do just that.

To send files from LINUX via Xmodem:
sx my_file.com

To receive files from the PC-8401
rx my_file.com

Now there is absolutely no excuse, not in the slightest to use a 27 inch widescreen monitor to interact with a high powered modern PC to write applications.

Finally, thanks to Mike Spooner for indirectly generating the idea behind this post.

See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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RetroChallenge 2017/10: Part 6

Writting New Software for an NEC PC-8401

As noted previously, the PC-8401 came sans BASIC interpreter, which was quite an anathema in the day. This lack of BASIC presents no real impediment in producing new software for the machine today, even back in the 80s a CPM targeted variety of BASIC could be sourced for the machine (if not a specific PC-8401 version). 30 years on, being equipt with a Z80A processor and the CPM 2.2 operating systems puts this laptop a good position for some software development.

Getting into BASIC

To start we'll need to copy BASIC interpreters onto the PC-8401. AS with all software, BASIC will be taking up valuable chunks of the 32k reserved as drive space. Our own BASIC text files will then need to fit in whatever space remains. Ideally we'd have a RAM extension, either a PC-8406A 32K RAM pack or a PC-8407A 128K pack, in order to program something of a reasonable size. Still even without a RAM pack we can at least try out a number of BASIC flavors.

Both the versions of BASIC mentioned below are available from Gary J. Webes' excellent NEC PC-8201 support site WEB8201, where he holds a selection of software for the NEC PC-8401. NEC PC-8401. Check out the NEC 8401A / 8500 File Collection portion of the File Downloads page.

Microsoft BASIC

In the stakes to use the greatest amount of memory possible, Microsoft BASIC wins hands down. The last CPM version 5.29 will take up huge 23.4k of 'disk space' and when executed leaves a little over 1k of active memory on the PC-8401 to play around with. On the plus side, it's the version of BASIC that's the most familiar, and baring some commands unavailable in the CPM version, there are a wealth of examples laying around to learn from.

Unfortunately the size of MS BASIC makes it a non stater, it's more of a curiosity than something of practical usage. There are compilers available for MS BASIC, though a you still require libraries on the disk to run complied applications. Due to lack of disk space, compilation would need to be run on a host computer before moving the end product over to the PC-8401.

ZBAS

Luckily there are other options, ZBAS is quite a usable option only requiring 16.4k, leaving us with some room to write programs interactively, and some space to save these applications to disk.

Interestingly and extra fortunately when saving files, ZBAS tokenises BASIC Commands, much like on a 128k ZX Spectrum. Thus allowing for some larger than expected applications to be saved on our rather limited 'solid' state storage.

If your going to leave BASIC laying around on the System, then ZBAS is clearly the one to have.

Moving to Modern 'C' Developement

While there are plenty of period development platforms and languages available for CPM, including 'C's and Pascals, you'll need to run these in a emulated environment as there is no room on the PC-8401 for such niceties. A load of CPM software and utilities are available on the retroarchive, although none of these programs are specific to the PC-8401.

Z88DK

Perhaps the easiest way to pursue software development for a CPM machine and the PC-8401 today is via the use of Z88dk. Z88dk is a 'C' compiler targeting TRS80s, Commodore 128s, Sinclair ZX81s and just about any machine containing a Z80 processor. Specifically for out purposes there is a dedicated CPM library.

In order to test Z88DK out with the PC-8401 I borrowed from an older ZX81 program I wrote up some time ago, "ZX Roman Numeral-Izer". The program is a simple roman numeral format checker, it takes Roman numerals as an argument and then correctly formats them to the agreed standards (Standards that even the Romans didn't always adhere to). After a couple of minor changes to remove some specific ZX81 extensions and put in some specific PC-8401-isations the project compiled perfectly.

If you're interested then the full source is below, bit of a rush and there will be better ways to achieve the same result I'm sure, still proof of concept proven.

NEC PC-8401 Roman Numeral-iser Listing

// To Compile for CPM do as below.
// zcc +cpm -lm -o rome.com rome.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef enum { true = 0, false = !true } bool;

static short isaNumArab[7] = {1, 5, 10,50,100,500,1000};
static char csaNumRome[8] = "ivxlcdm";

// Function Get Arabic value of Roman Numeral
short GetArabValue(char csMyNumerals[15]){

 char csMyNumeral[2];
 char csNumRome[2];

 short iNumberNow = 0;
 short iNumberLast = 0;
 short iNumberTotal = 0;

 short iCount1 = 0;
 short iCount2 = 0;

 bool bTest = false;
 bool bNegative = false;

 //Go through sMyNumerals input string backwards for easier rule matching
 for (iCount1=strlen (csMyNumerals)-1; iCount1>=0; iCount1--){
  strncpy(csMyNumeral, csMyNumerals+(iCount1*1), 1);
  csMyNumeral[1]='\0';

  for (iCount2=0; iCount2<=strlen(csaNumRome)-1; iCount2++){
   strncpy(csNumRome, csaNumRome+(iCount2*1), 1);
   csNumRome[1]='\0';
   bTest = strnicmp(csMyNumeral, csNumRome,1);

   if (bTest == true){
    iNumberNow = isaNumArab[iCount2];

    if ((iNumberNow > iNumberLast) || ((iNumberNow == iNumberLast) && (bNegative == false))){
     iNumberTotal = iNumberTotal + iNumberNow;
     bNegative = false;
    } else {
     iNumberTotal = iNumberTotal - iNumberNow;
     bNegative = true;
    }
   }
   iNumberLast = iNumberNow;
  }
 }

 return iNumberTotal;
}

// Function Get Roman value of Arabic Numeral
void PrintRomeNumerals(int iMyNumberArab){
 char csNumRome[16];
 char csMyNumerals[16];
 char csMyNumeral[2];

 short iTemp[16];

 short iNumberNow;

 short iCount1 = 0;
 short iCount2 = 0;
 short iCount3 = 15;

 memset(csNumRome,0,strlen(csNumRome));

 memset(iTemp, 0, sizeof(iTemp));

 if(iMyNumberArab>=4000){
  strcpy(csNumRome,"Max Value 3999");
 } else {

  itoa(iMyNumberArab,csMyNumerals,10);
  //csMyNumerals[15]='\0';
  //Go through sMyNumerals input string backwards for easier rule matching

  for (iCount1=strlen(csMyNumerals)-1; iCount1>=0; iCount1--){

   strncpy(csMyNumeral, csMyNumerals+(iCount1*1), 1);
   iNumberNow = atoi(csMyNumeral);

   switch (iNumberNow) {
    case 1: case 2: case 3:
     for (iCount2=0;iCount2<iNumberNow;iCount2++){

      iTemp[iCount3] = csaNumRome[(strlen(csMyNumerals)-1)*2-iCount1*2];

      iCount3--;
     }

    break;

    case 4:

      iTemp[iCount3] = csaNumRome[(strlen(csMyNumerals)-1)*2-iCount1*2+1];
      iTemp[iCount3-1] = csaNumRome[(strlen(csMyNumerals)-1)*2-iCount1*2];
      iCount3=iCount3-2;
    break;

    case 5: case 6: case 7: case 8:

     for (iCount2=0;iCount2<iNumberNow-5;iCount2++){

      iTemp[iCount3] = csaNumRome[(strlen(csMyNumerals)-1)*2-iCount1*2];
      iCount3--;
     }
     iTemp[iCount3] = csaNumRome[(strlen(csMyNumerals)-1)*2-iCount1*2+1];
     iCount3--;
    break;

    case 9:

     iTemp[iCount3] = csaNumRome[(strlen(csMyNumerals)-1)*2-iCount1*2+2];
     iTemp[iCount3-1] = csaNumRome[(strlen(csMyNumerals)-1)*2-iCount1*2];
     iCount3=iCount3-2;
    break;
   }

  }
 }

 printf("\n Correct Format: ");
 for (iCount2=0;iCount2<16;iCount2++){
  if(iTemp[iCount2]!=0){
   printf("%c",iTemp[iCount2]);
  }

 }
 printf("\n");

 return;
}


void BannerLine(short iLength, char cCharter){
 short iCount1 = 0;
 for (iCount1=0; iCount1<iLength; iCount1++){
   printf("%c",cCharter);
 }
}


void BannerSet(void){
 short iCount1 = 0;
 printf("\n");
 BannerLine(32,149);
 printf( "\n PC-8401 Roman Numeral-iser\n" );
 BannerLine(32,149);

 for(iCount1=0;iCount1<=strlen(csaNumRome)-1;iCount1++){

  printf("\n Numeral: %c = Numeric: %d",csaNumRome[iCount1],isaNumArab[iCount1]);
  if(iCount1 == strlen(csaNumRome)-1){
   printf("\n");
  }
 }

 BannerLine(32,149);

 printf("\n Roman Numeral Format Check\n");

 BannerLine(32,149);

}


short PressAnyKey(void){

 char chr;

 BannerLine(32,149);
 printf("\n Input Another Numeral? Y/N: ");
 chr = getchar();

 if(chr == 'n' || chr == 'N'){
  return 1;
 } else {
  return 0;
 }
}


main(void)
{

 char csMyNumerals[15];

 bool PressKey = true;

 char csMyNumberRome[15];
 int iMyNumberArab = 0;

 while( PressKey != false ) {

  BannerSet();

  printf("\n Roman Numerals: ");
  fgets(csMyNumerals,15,stdin);
  iMyNumberArab = GetArabValue(csMyNumerals);
  printf(" Numeric  Value: %d",iMyNumberArab);

  PrintRomeNumerals(iMyNumberArab);

  memset(csMyNumerals,0,strlen(csMyNumerals));
  memset(csMyNumberRome,0,strlen(csMyNumberRome));

  PressKey = PressAnyKey();

 }
}

See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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RetroChallenge 2017/10: Part 5

NEC PC-8401s' Capacitors & NiCd Sorted

Since discovering the leaky capacitors in the PC-8401s LCD module (last post, Part 4), I've replaced the problem components and the screen is now working without further issues. So, while had the main case opened I also decided to replace all the other potentially problem components and give the unit a good service.

I replaced all the capacitors with like for like values. The one exception being a 1200uf 25v, which is now a 1200uf 35v variety. The extra voltage level is not an issue, though the replacement capacitor is twice the length of the one it replaced, luckily there was space to lay it on it side.

The other remaining problem component was the 30 year old NiCd battery, which amazingly hadn't vomited it's guts all over the motherboard. The NiCd battery inside the PC-8401s is there to keep the DRAM and system clock ticking over should there be no main battery or indeed mains power. (No compact flash for 1985 user convenience).

1 Frand Super-Capacitor Battery Replacement

I decided to replace the battery with a 1 frand 5.5v super capacitor. I've previously made similar modifications to my Tandy M100 and M102 machines to good results, with RAM storage remaining intact for over a month before (until I got board waiting) I reapplied mains power. Similarly to the previous m100 modification, I bent the pins of the capacitor over horizontally before attaching wires which are the soldered on to the PCB. The capacitor itself is attached to the circuit board with double sided tape, keeping very firmly in place.

So next time it's back to doing something else arguably useful with a 30 year old computer.


See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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RetroChallenge 2017/10: Part 4

My NEC PC-8401s' LCD Module Faces Capacitor Issues

I'd noticed, well couldn't help noticing really that the PC-8401s' LCD screen would flicker, and every now again turn off unexpectedly after extended use. Over the last week the occurrences became more frequent. Interestingly or comfortingly the screen flickering has no effect on the Main Computer, everything stays resident, you can even continue typing while the screen is off. So what ever the problem? It is appeared localised to the LCD screen. Time to pry open the computer and see what's happening.

A quick look over the main board revealed nothing of immediate concern, though at some point I'll want to replace the NICAD backup battery and the 30 year old capacitors, thankfully though none of these components have been leaking. Semi confident the main board is okay it was time to crack open the LCD bezel, not the most convenient thing to do.

NEC PC-8401 Main Board

Unlike the main case the bezel is mostly held together with molded plastic clips, taking it apart took some considerable carefully spent time. Once off however it was immediately clear where the problem (hopefully the only problem) lay.

NEC PC-8401s' LCD Panel

We've got 2 exploded leaky electrolytic capacitors that need to be replacing, and while we're at it the other 10 should be swapped out for good measure. I guess considering the age of the computer this is not unexpected, all this is really part of the excitement of playing around with old hardware.

Some Picturesque Leaky Electrolytic Capacitors

Well then, before continuing any further it's of the the electronics supplier to procure some of these tiny caps, of which I have exactly none of in my parts draw.

As a quick aside the panel was manufactured by Epson.

Back view of the NEC PC-8401s' LCD Panel

See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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RetroChallenge 2017/10: Part 3

NEC PC-8401's Software-To-Go on the Go

It's time try out some of the PC- 8401's inbuilt software. Ideally I'll be wanting to create files that are usable outside the NEC PC-8401 1980's bubble. The software included in ROM was all quite cabable for the time our NEC was realeased into the wild, we should be able to make use of it to some extent today.

There are four software packages provided in ROM:

• Wordstar-To-Go: Micro Pro's word processing package, a portable version of the Wordstar. 
• Calc-To-Go: Portable version of Calc Star, also by Micro Pro. 
• Personal Filer: A flat file database program.
• Telecom: Modem and Serial communication tools.

Of those, the two packages likely to be of most use in the modern context are Wordstar-To-Go and Telecom and I'll quickly look at those now. Telecom is arguably of most importance as it will be required to move files and additional software on and off the computer. The limited 64k of available RAM (32 for storage and 32 as active memory) makes Telecom a necessity if we plan on doing anything useful in the longer term.

Getting the files on and off with Telecom

The Telecom application is quite effective, and thankfully includes the XModem transfer protocol, making file transfers reliable. Connecting to a regular PC requires a USB to serial cable and a NULL modem cable. Nothing odd here, I used standard off the shelf parts.

PC-8401 and LINUX CuteCom Talking

For software on the modern LINUX computer I'm using CuteCom as it's a windowed terminal communication program, the command line based Minicom works just as well for this though.

I found the default Telecom configurations need some tweaking. The baud rate was best set to 1200 for plain ASCII file transfers and terminal emulation, else the buffer got full and text was lost. For XModem the baud rate value can be up to 19200 (with some issues), 9600 provides issue free transfers. Other than that I set Stop bits to 1, as is the default value for just about everything else out there. The configurations can be saved to memory, so once setup it's all good to go next time.

XModem transfers in both directions work perfectly, making the task of installing software and transferring other files a simple.

With a basic configuration setup all the networking capacity of 1985 is at our fingertips. If I want to take the PC-8401BM out on a field trip, or write up blog pages on the go, then we can rest easy knowing all that hard work is easily transfered back to a regular PC.

With basic communications configures it's time to look at using some of the built in productivity software.

NEC PC-8401BM Telecom Default Configuration
OPTION	DEFAULT	DISCRIPTION
CONNECTION	RS-232C	Internal Modem or RS-232C
PROTOCOL	OFF	ON for modem7 / xmodem, OFF for ASCII transfers
SPEED	9600	150 - 19200 baud
WORD LENGTH	8	7 or 8 bits per character
SI/SO	ON	Shift In/Shift Out sequence
STOP BITS	2	1, 1.5 or 2/td>
PARITY	NO	NO,EVEN,ODD,IGNORE. Ignore only effective when STOP BITS set to 8
XON/XOFF	ON	ON or OFF
ECHO	OFF	ON or OFF
CHAR WRAP	ON	ON or OFF
NEW LINE	OFF	ON or OFF
PPS	10	10 or 20. Pulse Per Second, Used for modem dialing
LABEL	OFF	ON or OFF. Displays the Function key values
DEL CODE	7F	7FH (DEL) or 08H (BS)
LF SUP.	ON	ON or OFF. ON Suppresses LF codes ignored during uploads
LINE DELAY	0	1 - 7. Delay ACK response.
PRINT	OFF	ON or OFF. Echo session on a printer
SAVE	OFF	Save Telecom configuration on exit

---

Can we Wordstar-To-Go?

Wordstar may still be a perfectly usable as word processor, with one proviso, that we have some sort of document conversion utility. This is where we start running into problems on the modern PC side. It seems that we're now so far removed from Wordstars historical dominance in the marketplace that pre-existing conversion tools, even thoughs designed for 'newer' platforms are themselves so out of date emulation is required to run them. (I find this news a touch disturbing).

Over at the Way Back Machine (love that machine), the remains of the WordStar Resource Site provides downloads to various converters, Sadly, I've tried a number of the conversion utilities without any luck this far. They all specify conversion capabilities extending to DOS and Windows Wordstar files exclusively, so the PC-8401s Wordstar-To-Go files will need to undergo a CPM to DOS conversion first.

Failing conversion utilities, there are two other options available, both built into our trusty PC-8401. Firstly, Wordstar-To-Go can produce simple text files that need no conversion. This is the easiest option to use.

The second options is available during file transfers. When sending files with the Telecom package there is an option to convert Wordstar files to plain text. This produces a similar result to using plain text to start with, but not quite. Conversion ignores continuous paragraphs, so what appears to be the end of a line in a Wordstar file (lines are by default 65 character long) is the end of a line, meaning all paragraphs would have to reformatted to be contiguous. Note that Wordstar itself treats paragraphs the same way. The text will appear  exactly as formatted on screen in Wordstar, minus control characters and .dot commands.

The best explanation is a simple example, below are three version of the same file. The text was justified in the Wordstar formatted files.

RAW Wordstar File: 

Thå  quicë  browî dingï jumpeä oveò thå lazù  fox®  Thå  kangaroï 
jumped over the dingo.

No animals were harmed in the above test sentence.

Wordstar File with Special Characters Removed During File Transfer

The  quick  brown dingo jumped over the lazy  fox.  The  kangaroo 
jumped over the dingo.

No animals were harmed in the above test sentence.

 Plain Text File

The quick brown dingo jumped over the lazy fox. The kangaroo jumped over the dingo.

No animals were harmed in the above test sentence.

So is Wordstar on the PC-8401 still usable in the modern context? Yes, but with some serious limitations for the time being. There would be an interesting RetroChallenge project in writing a decent conversion utility.


See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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RetroChallenge 2017/10: Part 2

An NEC PC-8401 Quick Guide Book for the Internet Archive

As we know from the previous blog entry, there was absolutely no documentation on the NEC PC-8401BM contained within the Internet Archive. Today I thought it might be a good idea to start addressing this situation.

PC-8401BM Manuals

I have in my possession the 4 Australian Manuals and the Quick Start Guide originally packaged with the PC-8401BM. The easiest of these to scan and make available to the Archive is the Quick Start Guide, this being the only book conveniently with a ring style binding. So naturally I've started here.

Being in a spiral binder the pages were easy to remove, this has allowed for quite a nice scan overall. The other manuals however are going to be slightly more of a challenge to pull clean copies from. So after an hour or so plus some cleaning up time, I'm happy to report the Quick Start Guide is now available to all those who seek it's wisdom.

I should say the Guide is mostly available, there are unfortunately 2 pages missing, pages 34 and 35. These pages should form the first part of the Calc-To-Go section in the book. Not the best of situations, still the rest of the book is complete and pretty much gives all the information the casual PC-8401BM user is likely to require.

I'm not quite sure on the best way to proceed in scanning the remaining books. All the manuals are in exceptional condition, as such I don't wish to ruin them by either pressing the books to firmly against the scanner and cracking the spines, or indeed by removing the spines. It certainly would be handy to have access to a book scanner. (If anybody out there is feeling generous, please send your best book scanner free of charge ASAP).

As a bonus, I thought I'd clean up one of the pull out / fold down sections of the Guide illustrating the many extended devices NEC produced to dock and otherwise attach to the PC-8401BM. These include Data Recorders, Disk Drives, RAM Cartridges and CRT / Monitor adapters. The product codes of all these items is conveniently listed. For those interested in acquiring computer extensions today, the NEC product codes it could well make Ebay and Craigslist searches a little easier (you could try NEC directly in some sort of vain last hope of course).

The PC-8401BM Connection of Peripherals fold out, because everybody loves a good diagram.

The Guide Book is now avaliable and indexed at the Internet Archive: https://archive.org/details/NecPortableComputerPc-8401bmQuickGuide


See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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RetroChallenge 2017/10: Part 1

The NEC PC-8401 a Starlet in the Press?

NEC PC-8401A Review in Creative Computing Magazine

The NEC PC-8401, AKA the Starlet premiered at the November 1984 Comdex show, a year after the Tandy Model 100 made its splash. (As an aside, glimpse the Model 100 at the 1983 show in this remarkable footage). The rise of the portable computing has begun, and a new world order soon to be dominated by IBM compatibility is starting to play out. Where does our little NEC offering fit in?

Unfortunately for us, there are scant references to the PC-8401BM in its contemporary computer press, or so it would appear by the lack of articles available on the internet archive. This is a trend that continues, even against the current rise of 'retro' computing within the global consciousness. The 1984 Comex appearance of the PC-8401 is however noted in Infoworld 1984-12-17 magazine.

That the PC-8401 lacks a perceptible public success may not accurately indicate it market penetration, particularly considering its main reason for being was to serve a business oriented market. It is therefore not so unsurprising that hobbyists of the period may have ignored the PC-8401 as expensive business machine, with that the business positioning still limiting any appeal for today's retro collectors or enthusiast.

The only extensive review of the PC-8401 from the time period available over at the Internet Archive is a write up in the March 1985 issue of Creative Computing Magazine by David H Ahl's. The review is based around the model PC-8401A not the PC-8401BM which I'll be using over the course of the RetroChallenge.

Overall the Creative Computing review is a positive one, with the only major criticism levelled at the small display area on the Model 8401A, an issue addressed on the 8401BM. The included software, built into the machines ROMS is noted favourably, Wordstar-To-Go which is found to lacking in some of features available in the desktop version, a minor let down and scores only reluctant approval.

Interestingly what we could surmise as the reasons behind the failure of the 8401 to enter the popular consciousness are highlighted at the end of the Creative Computing article. Firstly NECs failure to include BASIC in ROM at once precludes the machine from hobbyist usage. While the lack of programming languages provided by default on computers today is a non-issue, in 1984 this was often the pathway for home hackers to explore a computers capacities. Secondly, and more interestingly it seems NEC had a less than stellar marketing division (at least outside of Japan).

In retrospect, NEC should possibly have paid close attention to Creative Computing closing summary, as now the trail and magazine reviews go cold. There are of course many gaps in the Internet Archives collection of 80s computer magazines, even so the range of coverage still available and the lack of NEC PC8401 mentions in them would seem to confirm David H Ahl's concerns.

Luckily the target business market did procure and use enough PC-8401s that they haven't all gone to landfill, and somehow a PC-8401BM even managed to keep it's manuals intact, make its way to me and so we'll have something more to examine for the month long RetroChallenge.

The rather colourful NEC PC-8401BM User Guides.

See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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RetroChallenge 2017/10: Getting to know the NEC PC-8401BM

It's almost time for RetroChallenge 2017/10, a month long opportunity to focus in on a single project, share and document your activities and finally share the results with the wider retro community. This sounded like a good excuse for some retro adventure, so I've thrown my hat into the ring and decided to spend the time focusing in on the portable 'powerhouse' that is the NEC PC-8401BM.

My NEC PC-8401BM in the wilderness, Compute anywhere with 1985 style.

Strangely there is very little information on the inter-tubes about the NEC PC-8401BM, AKA the NEC PC-8401A and AKA NEC Starlet. As luck would have it one has fallen into my lap very recently, and just in time for the Retrochallenge.

During October I'll explore this tidy 'little' laptop styled machine, examin the available online articles, work through the machines manuals and generally explore how this computer can be used today, practically or otherwise.

Exact outcome unknown, we'll end up where curiosity takes us.


See RetroChallenge Intro, Part 1, Part_2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8

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The TRS-80 Model 100 MyTeSed is Alive

After a bit of a wait the MyTeSed for the TSR-80 Model 100 enters the construction stage. A simple SD card reader is in sight, though not until a few challenges are met. Mostly the build went smoothly, mostly being down to one misguided assumption in turn inducing lot of time spent waiting.

Two MyTeSeds, one attached to a Model 102 and the other connected a Model 100

This is the first time I've had PCBs produced by a fabrication house, for every other project I've made them myself. The end result is a really impressed impressive sight, and the quality is quite amazing. The quality of the PCB lends a certain confidence to the endeavour of populating it.

Construction started out quite simply, first mounting all the loose components onto the PCB. A snag to the master plan appeared when it came time to mount the SD card module. I'd soldered some header pins to the PCB and added a couple of layered of doubled sided tape to hold the module firmly. The header pins I would very soon have to remove again.

I had assumed I'd be able to de-solder the right angled header pins from the micro SD module and then attach the module to the pins I'd soldered onto the main PCB. This of course turned out to be a very bad idea, leading ultimately to the complete destruction of a module. It seems the modules PCBs just aren't up to that kind of meddling. The lesson here I suppose is to never assume anything will work quite as planned.

My misguided assumption cost me a couple of weeks, I only had the one SD module to break, I found myself needing toprocure some more modules from China, leaving me floundering before proceeding any further. Oh well, live and learn.

A little wiser and with some new modules in hand, the easiest solution to my problem was to attach some cutoffs to the bottom of of an SD card module and then solder those into the PCB mounting holes as originally intended. I'd probably choose to mount the modules in the same way next time around as it worked near enough to originally planned.

I'd sensibly procured a number of spare SD modules, so decided to build up a second MyTeSed, allowing me to make one very minor change. The first build used a full length 26 pin IDC socket, this really isn't needed as there are only 3 pins in use, from pin 1 to 3 (GND,TX and RX). I switched to a 10 pin IDC socket, this makes the IDC cable a lot easier to construct, a lot easier to connect, easier to move around and ever so slightly cheaper to build (if a few cents are of concern).

Lastly I mounted the Arduino Nanos, I chose to solder the first Nano directly to the initial PCB build, on the second board I mounted on a couple of pin sockets first. This second option is the recommended choice if planning to re-use the Nanos' in other projects, though I figured I'll have at least one of these SD readers around for some time to come.

 The good news is that after all the waiting for parts the end result worked as expected. The only really major component of the initial project left to sort out is software, again as I'd managed to kill the original SD module I had nothing to test with until I got to this point. I've subsequently had some time move forwardon that, which will form the basis of the next post.

The two versions of the MyTeSed, the first build with full 26 pin IDC cable (9v and battery attached)

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