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...

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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...

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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...

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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...

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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...

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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...

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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...

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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...

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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...

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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...

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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...

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Model 100 micro SD Card reader, the MyTeSed

After the initial testing with a full sized SD card reader shield and Ardunio Uno, I wanted to know how easy it would be to shrink the TRS-80 Model 100 SD card interfaces size down to something a little more acceptable. I thought about building the whole design from the ground up, in the end the abundance of cheap modules from China can't be beaten on price (or convenience). Before getting into the excitement of the details, the other...

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ZX81 Video Monitor Perfection?

A while ago now I fitted the very cool and reasonably priced ZXCCB composite video mod into a ZX81, yielding a much improved video experience, yet this is only half the story in the quest for retro ZX81 video perfection. There is many a web page or YouTube video devoted to video outputs on retro computers and gaming consoles. Mostly these deal with the somewhat later computing or console incarnations such as the Sega Mega Drive, Nintendo...

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Using SD Cards with the TRS-80 Model 100

Most retro-computers have some form of SD or Compact Flash storage options available these days. The TRS-80 Model 100, Tandy 102 and Tandy 200 were no exception, and these micros had such a device not so long ago, the NADSBox. Most unfortunately it appears the NADSBox can no longer be sourced. So what to do now? Well build my own, very cut-down version I suppose is the obvious answer. Loading files into the Model 100 As an 80's...

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USB Mouse For The ZX81 And ZXpand (Part 2)

It's been a while since the first part of this article, some exciting developments happened to the ZXpand in between and I wanted to test the interfaces functionality out on the brand new ZXpand+ hardware before posting. I've also given the interface a little moniker, "ZeaMouse". Anyway, enough fluffing around, down to the specifics. As previously mentioned (in Part 1: USB Mouse For The ZX81 And ZXpand), the USB mouse interface relies...

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