Ampliación RAM Camputers Lynx 48K a 96K. Ram Expansion

[Peter Todd]

Queda abierto este hilo para documentar y generar un procedimiento que nos permita ampliar los Lynx 48K a 96K Ram.
This thread is open to document and create a process that allows us to expand the 48K Lynx to 96K Ram .

oh JLtursan - the Memory upgrade from 48k to 96k is quite easy to do - just swap some DRAM chips, a new ROM and a couple of links to change on the PCB.

The SPLYNX96 is a more difficult modification involving several wires and track cutting.

[jltursan]

w00t?!, that 96K upgrade, is it documented somewhere?. I suppose the ROM is the one from the 96K model found commonly in the web, Im just missing the info about the PCB links

EDIT: Looking for info Ive found some pages that point that you only need to replace the main PCBs 16K ICs with 64K Ics and accomodate some PCB links, most probably used to drive A7 signal and replace +12V with +5V. About the roms, I just need to burn some EPROMs with the V2 version. The third and extra ROMm, although is only 4K, comes as a 8KB file; so being a 28 pin socket, I suppose that I need to fit a 2764 and burn a full 8KB file with both halves filled with the first 4KB of the original ROM file. Just to be sure, Ill check the spare ROM socket to find how A12 is driven.

EDIT 2: Mmm, I think I got it all. The links are LK5, LK8 and LK9:

LK5: Cut from B (+5V) and solder to A (A13/15??, not clear in the schematics; but seems to be IC18s pin 12)
LK8: Cut to disable -5V supply
LK9: Cut from B (+12V) and solder to A (+5V)

Now you have the signal and voltages needed by the 4164 ICs

Ive also found that if the Lynx detects 96KB, the V2 ROM makes computer beep twice at boot. Ill get my Lynx and Ill give it a try as soon as possible

[Peter Todd]

Hi , yes that looks correct. I am not at home at present but I will check when I return.

There are a couple of versions of the 96 roms you could use. Some have the ability to scroll
The display. I will see what there is available on release for you. Some roms are specifically not available
For download on the request of the authors.

If you look at the Splynx modifications you could do those as well it only takes 20mins and then you can run some Spectrum games.

[jltursan]

Thanks Peter!, that extra scroll feature sounds nice!.

Btw, in your schematics repository, file "Lynx 48K 96K Circuit Diagram 600dpi.png" seems to be broken (or maybe theres some kind of download limit). I havent been able to download a complete copy. Luckily, the RAM diagram is in the downloaded part
Also, does it exists a disassembled ROM listing (from the ones freely availables, of course)?.

[ron]

Esto ya tiene mejor pinta xD
Venga, entre la ampliación de RAM, las ideas del Clon de Silicebit, los conocimientos de jltursan y la ayuda de Pete, 2014 va a ser el año del Lince

[Peter Todd]

Here are some Disassembly files - please take notice of the README

CPDT Disassembly Files V1.0.zip

CPDT Disassembly Files 1.0

(531.71 KiB) Descargado 172 veces

PEte!

[Peter Todd]

For the 2B revision board I have in front of me:

I have 4564 - 15 x 8 in the lower LHS sockets, the rest are all standard 4116

this will prob. be a 5v equiv. of the 4164 we will have to check.

So I have
LK1 cut (-5v supply unused)
LK2 (Middle) Connected upper both links (5v power and A13/15 connected)

There are quite a few mistakes in the Schematics you will find.

I think you are trying to convert the video RAM with 7 & 8

That isnt doable on the 96k unless you start getting into modifying for 96k 80 COlumn CPM mode.

You only need to upgrade the Base RAM, not VRAM

[jltursan]

Whoops, so Ill better compare the schematics info with my board rev, without real good schematics this can be risky.
Ill take some pics of my PCB before modifying the traces, Ill also look for the links you pointed, they seem fine; but I miss a link to unuse +12V (maybe LK2?).

The 4564 are a direct drop in replacement for the 4164 ICs, no worries here.

Btw, thanks for the sources!

[jltursan]

Ive checked my PCB and another 48K v3 schematics (I suppose that v3 will be close enough to v2, my own PCB) and heres what Ive found:

Lynx 48K v3 schematics:


My PCB (v2):


As you must guess, LK1 is closed and LK2 (middle) has both lower links closed. Ive checked continuity and they indeed provide +5V and +12V as they are now.

The 96K configuration must be:


Red lines are cutting marks and green lines means a closed link. Is it correct?

As the 4116 are already mounted in sockets I only need to replace them with 4164 ICs

The ROMs (IC45 & IC46) are already the Lynx96K versions. Ive compared them with Pales ROMs and they are equal except a padding byte in one of them

[Peter Todd]

Yes thats exactly what I have here

padding byte? at the end or beginning? do yu have a Davis AND Suzy ROM or just a Davis (from listing the first page)

[Peter Todd]

ah you must have an L014 ROM as I call it (where Davis used to be in the ROM there is now an L014)

[jltursan]

Right, thats what I have, a "Davis" & "L014" ROMs. See the ones attached to my other post

Im going to proceed with the upgrade...

[Peter Todd]

Do you have a third ROM to stick in?

You can use the one from Pale or this one from Denmark, Im checking on Scorpion for you.

[Peter Todd]

hmm attachment here?

danrom3.zip

Danish 96K ROM

(5.03 KiB) Descargado 137 veces

[jltursan]

Ive used lynx96-3.rom from Pale. Ive created an 8KB file with two 4KB first halves and they seem to work fine . As Ive checked A12 in IC44 socket and found that is not tied to GND, Im not sure how the Lynx will read the ROM; so Ive filled the full 8KB.

Anyway, the 96KB are working!:


MEM shows the correct mem size, Lynx beeps twice at boot... and KLAXON, EXPLODE, etc. doesnt work

Theres only a problem (well, really two):

1) The display is not stable, it has a slight "shaking", most probably caused by lack of power supply. Ive used 150ns 64Kx1 ICs, maybe theyre drawing too much power...
2) Ive damaged a pair of decoupling RAM capacitors (473Z=47nF). Although I think the machine can live with this, I best prefer to replace them, not sure if they have something to do with problem 1)

All in all, an easy job!

Thanks Pete!

Btw, are there any differences between your lynx96-3.rom and Dans one?

[ron]

Pete !

insert attach.png (24.02 KiB) Visto 3217 veces