Zen Z80 editor-assembler for the Grant Searle & RC2014mini/micro/classic

[DavidMS]

Originally Posted by ortek_service

Yes, and the Z80-SIO is probably much-rarer than the CPU - as not many Z80 systems had a Z80-SIO IC fitted as standard (sometimes opting for an 8251 etc, if only Asynchronous-serial was required - like in the Tatung Einstein - Maybe it was a bit cheaper?)

Gemini (successor to NASCOM) had a basic networking solution for their office setup, one of my jobs during my graduate placement with them was sanding off the details from the 'networking' chip - which they sort of implied was something special - it was in reality a Z80 SIO ...

[SiriusHardware]

Briefly aside, I was offered a complete working Gemini system from a customer's premises when it became redundant as it was being replaced with networked PCs, this was early-mid 90s. It was complete with matching monitor and keyboard and had been doing its job as the heart of an alarm receiving centre for a good few years before then.

Had I been aware of its NASCOM heritage at the time, I might have saved it. But... I didn't. When it was running it was never possible for me to get near it and it was so reliable it never needed any attention. I assume it must have run CP/M?

[DavidMS]

Originally Posted by SiriusHardware

Briefly aside, I was offered a complete working Gemini system from a customer's premises when it became redundant as it was being replaced with networked PCs, this was early-mid 90s. It was complete with matching monitor and keyboard and had been doing its job as the heart of an alarm receiving centre for a good few years before then.

Had I been aware of its NASCOM heritage at the time, I might have saved it. But... I didn't. When it was running it was never possible for me to get near it and it was so reliable it never needed any attention. I assume it must have run CP/M?

Yes, it would have been running CP/M, they did have their own operating system but I don't think that supported floppy / hard disks, so you were effectively forced to go down the CP/M route.

[Phil__G]

Or Polydos, that was our choice at BT.
Polydos didnt have the start-at-100h imposition that CP/M has and was easier to integrate into the Nascom/Gemini memory map.

Also, whilst you were saving up for a disk system, Gemini had RP/M which allowed you to develop CP/M software with storage on cassette tape!
RP/M was a 'cp/mified' monitor that supported most bdos calls such that simple CP/M programs wouldnt know the difference.
Once an application was loaded (say MBASIC etc), RP/M allowed you to stream just one file on tape.

[DavidMS]

Originally Posted by Phil__G

Or Polydos, that was our choice at BT.
Polydos didnt have the start-at-100h imposition that CP/M has and was easier to integrate into the Nascom/Gemini memory map.

Also, whilst you were saving up for a disk system, Gemini had RP/M which allowed you to develop CP/M software with storage on cassette tape!
RP/M was a 'cp/mified' monitor that supported most bdos calls such that simple CP/M programs wouldnt know the difference.
Once an application was loaded (say MBASIC etc), RP/M allowed you to stream just one file on tape.

I very much liked Polydos, one of my long term to-dos is to un CP/M my NASCOM 2 and re-install Polydos

[Phil__G]

Neal Crook is your man!

[DavidMS]

Originally Posted by Phil__G

Neal Crook is your man!

we have spoken

[Phil__G]

I've managed to recover some of my old Zen source from 40-year-old cassette tapes, not 100% yet but working on it... unfortunately I've not found my biggest Zen project which was an RTTY transceiver with buffered I/O, memories, mailbox, forwarding etc... had its own keyboard & video routines... still looking as there are quite a few unmarked tapes and some faded printouts (some from a Creed 7B!). I could do with a better mono cassette tape player, this cheap Walkman is pretty poor. Not sure if they're even available now! I've been using Zen extensively on the Grant Searle Z80s and its been good as gold, proper timewarp computing
Cheers
Phil

[DavidMS]

Originally Posted by Phil__G

I've managed to recover some of my old Zen source from 40-year-old cassette tapes, not 100% yet but working on it... unfortunately I've not found my biggest Zen project which was an RTTY transceiver with buffered I/O, memories, mailbox, forwarding etc... had its own keyboard & video routines... still looking as there are quite a few unmarked tapes and some faded printouts (some from a Creed 7B!). I could do with a better mono cassette tape player, this cheap Walkman is pretty poor. Not sure if they're even available now! I've been using Zen extensively on the Grant Searle Z80s and its been good as gold, proper timewarp computing
Cheers
Phil

You might do better going the other way and look at getting a 2nd hand hifi 'separate' cassette player / recorder and building a simple amplifier to take the line level to what you are looking for.

[ortek_service]

Originally Posted by DavidMS

You might do better going the other way and look at getting a 2nd hand hifi 'separate' cassette player / recorder and building a simple amplifier to take the line level to what you are looking for.

Back in the 80's, I used to use the headphone socket on a Hi-Fi cassette deck (think I wedged a mono plug not fully-in, to get both channels that normally go via resistors form LS outputs to that), directly into cassette port of the BBC Micro. And this worked quite-well on that (With decent TDK etc cassettes, after discovering those 'WH Smith C12 Computer Cassettes' were truly not fit for purpose - playing back > 6dB lower than recorded level and lots of dropouts!)
But not sure if this would be high-enough level for all computers / some may need an adjustable volume-control for optimum results, from my memories of previously using a Spectrum with Philips cassette recorders (I bought a new deluxe model, with adjustable treble, bass and pitch? that didn't seem to work as well as previous one I had that gave lots of mains-hum). I also require having to seemingly re-adjust the head azimuth for highest frequency on a per-cassette basis to get them to load.

I did see a few years ago, that Tesco were selling Walkman's (Not Sony, but some obscure brand) that also recorded (Built-in Mic?) for around £20 - as well as blank audio cassettes (that have rather out-lived VHS & MiniDisc blanks, they used to sell many years ago). It seems pre-recorded cassettes are now making a come-back, and used ones were selling for more than many CD's / LP's at a record fair I went to again on Record Store Day.

[ScottishColin]

Phil - I have a spare Acorn ANF-03 which you're welcome to have if you want to try it; let me know.

https://www.retro-kit.co.uk/page.cfm...corder-ANF-03/

Colin.

[Phil__G]

OOOhh that sounds ideal!
PM sent!