512K memory upgrade for the Model I - its here!

[TRS-Ian]

FINALLY - I have the 512K (or 256K if you prefer) upgrade for the Model I. It's a variation on the old Anitek Supermem upgrade from the late 1980s.

I'm hoping this will be the beginning of a series of three memory upgrades... the other two being for the Model III and 4.

http://www.ebay.com/itm/512K-Supermem-upgrade-kit-board-for-Tandy-Radio-Shack-TRS-80-Model-I-computer-/152582555415?hash=item2386a10717:g:twMAAOSwIjJZPhFP

I have the parts on hand to make about 10 of them. Drop me a line if interested.



Cheers,

Ian.

 

[pski]

Mav, first, it's great to see these offered! Thanks!

Do you know if there is any documentation that tells how to program to use this extra memory? I couldn't find any.

Also, for the M III/4, are you going to be offering the Megamem?

one more. I just read the eBay description. Where do all the RAM chips go? Do we replace the existing RAM in the EI?

 

[TRS-Ian]

Included is the original instruction manual. In it shows how to bank switch in Basic (using the OUT 67,N command where N is the 32K bank number) and details the hardware modification to the system.

The memory chips replace the original 16K chips, so for 256K you just install the chips and for 512K you need to piggyback 8 more chips on top of the first set. Modifications are made to the PCB to change the 5V to the correct pins on the 41256s and disable the 12V supply (not needed). The EI Ram is just removed and a couple traces cut to disable memory addressing in the EI.

I've made the manual available for download from here: http://ianmav.customer.netspace.net.au/downloads/Alpha%20SuperMEM%20Installation%20Manual%20(1987)(Alpha%20Technology).zip

Re. the other machines. I located a MegaMem card for the Model 4 and sent it to P.H for reverse engineering, but it was not successful due to problems with the card, so we need to locate another one to continue development on the Model 4 card. Model III... we've yet to find one, unfortunately. I'm hoping that by releasing the Carte Supermem 512K to the public it will give a much needed shot in the arm for people to search out and find the Model III and 4 versions.

Ian.

 

[Tibs]

Or the XL8er? That had lots of LDOS support already, wondering if it would be viable/possible?

 

[TRS-Ian]

If you've ever seen an XLR8r you'll know its certainly the most complicated and crowded board released at the time. While reverse engineering anything is possible, the XLR8r would be up there with the most difficult to reproduce.

@pski: I believe Lowen knows a bit about the bank switching capabilities of the expanded memory TRS-80s. Hopefully he'll read this and offer some words of support.

Ian.

 

[pjhacnau]

If you've ever seen an XLR8r you'll know its certainly the most complicated and crowded board released at the time. While reverse engineering anything is possible, the XLR8r would be up there with the most difficult to reproduce.

So the two speedup boards I'm aware of are the XLR8 and the Seatronics (though I've seen references to "other speedups"). is there a canonical list somewhere? What would, given their respective complexities, be the easiest to reporduce (given you could find one)?

Also how hard would it be to drop a z80h in, add faster memory, and a faster clock? I'm assuming something would break, but does anyone have an idea of how much?

PJH

 

[Tibs]

Actually I've never seen one, and would love to get my hands on one. (XLR8r). I remember reading about those quite lustfully.

 

[lowen]

Re: bank switching. I wrote a driver for the 80 micro 320k memory mod for LS-DOS 6, and I've often wanted to do one for the megamem, but never had one.

As to the XLR8er, I've been looking for a while about a modern reproduction based on the P112 or similar (the SB180 Mark IV by John Coffman would be cool, too, but that design is for noncommercial use only).

A true reverse engineering of the XLR8er would be very cool, but converting to use the PLCC68 package for the Z180 processor would make the layout easier than the fine-pitch DIP64. Ian, do you have one you could take really good photos of?

Heh, I've even considered using the 4 or 4p as an I/O-only expansion peripheral for the CPU280.

 

[pski]

Anyone know where to find the Model I Alpha Tech RAMDRIVE software? I see the usual archives only have the Model 4 version.

 

[Gazza]

A true reverse engineering of the XLR8er would be very cool, but converting to use the PLCC68 package for the Z180 processor would make the layout easier than the fine-pitch DIP64. Ian, do you have one you could take really good photos of?

I have an XLR8er running in one of my 4Ps but this computer is extensively modified and I'm terrified of removing the cover.
Tis a bit like an overfilled suitcase.

Agree, the PLCC68 would be the better option if someone wants to reverse engineer the XLR8er. Also supports 1 meg unlike the original Hitachi 64180 used in the XLR8er which is limited to 512K, but as everyone knows we will never need more than 640K.
Gazza

 

[jharre]

Haven't looked at my XLR8er for ages, so I pulled it out for a 'photo op'. It looks like this one uses a four-layer PCB that might be hard to copy.

 

[P.H]

Bonjour,
Nothing indicates that it is a 4 layer, the "PCB" has no regulatory indication that it is a 4 layer. In addition, a 4 layer coating is not very difficult and does not cost very much in "made in China". At least it is necessary to make a diagram of this card to be able to help it in case of problem. For the DIP64 no problem why use a PLCC68? 2 rows of 32 sockets with good separation and work is complete.
I am a little overbooked with my HIFI-COLOR M1 in 50Hz that I pass in 60Hz.
I'll find the solution?
But if I had a similar card in my hands, I will do at least its schema.
The only problem that keeps me from copying, are the PAL and GAL locked
A+
Pascal

Rien n'indique que c'est un 4 couches, le "PCB" n'a pas l’indication réglementaire que c'est un 4 couches. De-plus refaire un 4 couches n'est pas très difficile et ne coute pas très cher en "made in China". http://jacohk.com/services.asp?id=8
Il faudrait au moins faire un schéma de cette carte pour pouvoir la dépanner en cas de problème. Pour le DIP64 pas de problème pourquoi utiliser un PLCC68? 2 rangées de 32 douilles avec le bon écartement et le travail est terminé.
Je suis un peu surbooké avec ma "HIFI-COLOR M1 en 50Hz" que je passe en 60Hz.
Je vais trouver la solution?
Mais si j'avais une carte similaire dans les mains, je ferai bien au minimum son schéma.
Le seul problème qui m’empêche la copie, se sont les PAL et GAL verrouillés

 

[Jay Newirth]

Ian

Have you tested it yet? Are you planning to post on UTUBE?
Would like to test one out in the near future

Jay