I need your help: Burn an EPROM for SIO2BT

[manterola]

Hi guys and gals,

I am having problems with my OS EPROM. The EPROM has 4 OS version but I toggle b/w 2 of them with a switch. The first is the one for SIO2BT (it includes cold reset with Shift+Reset and modified timing for disk access), and the second is a regular unaltered OS XE version (it came with my 65XE and it include the self test for the extra memory).

Now The second one start random fails that send me directly to the self test, o just green or black screen, but sometimes work...

I've been looking for a EPROM writer but they are still out of my budget and in my case will be barely used.

If someone can create one for me, it will be greatly appreciated. If it is in USA is better so I can pay a decent postage and the price of the materials..

Thanks in advance.

 

[Albert]

I'd be glad to program an EPROM and send it to you. What type of EPROM is required?

 

..Al

[+Nezgar]

My TL866 is pretty cheap on eBay from china and supports an amazing # of chip types. (for windows machines) I've burned 2732, 2764 27128, 27256, and a few larger types very easily.

 

Regardless, you indicated this would be a 1-time job. I'm in Canada, but postage to USA for something small like an eprom is only about $3, , eprom $3-5, so I'd be happy to burn what you like and drop it in the mail for my cost. The challenge will only be sourcing the 2, or 4 specific OS images you want... (and which order)

 

BUT. I'm curious how your multi-os mod is wired up, as maybe your existing chip is actually OK, but something in the wiring or other components are bad. The symptoms you mention seem like what I've seen when the extra address lines on a 27256 or 27512 are left floating, which makes the chip spuriously 'switch banks' and crashing the system. Is your original XE OS using the original mask ROM (and is it working?) And what is the type of eprom? With 4 OS I'm guessing 27C512

 

If the existing eprom really is suspect, me (or whomever else) can try reading it in the eprom programmer and checking the data...

[xrbrevin]

another thumbs up for the TL866

with it you can mod carts, drives, OS-ROMs, MMUs, build SIO devices etc

[manterola]

Thanks for the quick response.

I check and recheck the OS selection circuit and it is OK. I tried with other eprom from other compu with sio2bt and it worked, so I assume the circuit is OK.

The circuit connects the pin 27 (A14) with pin 28 (VCC) with a pull up resistor, to keep the A14 high, when it is in SIO2BT mode (alternative OS). When I move the switch it connects A14 to GND (and at the same time power off the BT module). In this position (A14 low) the original atari XE OS is visible.

 

Since it is a m27c512 four OS version are in the eprom: QMEG / QMEGBT / XE / XEBT . I am ok with just 2: XE/XEBT (in that order, BT is bluetooth) so a m27c256 should be enough.

 

The ROMs are attached.

Now I have a nice problem, I don't know who to ask to do this more me. Thank you guys for offering help. I will send PM with my address.

 

Thanks again,

 

Mauricio

 

ps: TL866 is still >$80 right? or I am searching the net wrong?

130xeos.rom

siobt2os.rom

Edited September 8, 2018 by manterola

[Albert]

Does it matter what order the images are on the EPROM?

 

..Al

[+Nezgar]

How about $44 + $2.45 shipping. Doesn't include all the extra adapters for TSOP's and stuff, not needed for most vintage eproms: https://www.ebay.com/itm/232365295662/

[manterola]

Just to keep it the same... First 130xe s then sio2bt os

Edit: changed the order

Edited September 8, 2018 by manterola

[xrbrevin]

search ebay for "TL866CS"

this can also be firmware modded to a higher spec if you wish

[Kyle22]

search ebay for "TL866CS"

this can also be firmware modded to a higher spec if you wish

But WATCH OUT for the BOMB that they put into a recent firmware version. DO NOT UPGRADE. Search for the subject here, and elsewhere. There is a POISON version of the Firmware out there.

Please pay attention. I got bitten by this myself because I had to replicate the incident that was reported. My TL866 is now a brick. Yeah, I will open it up and solder that resistor across those 2 points and re-flash it. Some day. I can still burn EPROMS because I still have my Sunrise Z1000B Universal Programmer. These things were big shit back in the day.