I will find a 27256 and try it on my board. I wouldn't think 27C256 would make a difference... but perhaps it might in this case, since we are running the 7805C near its limits. In the mean time, you can burn the candle from the other end by finding a 27C256. I can mail some of these chips to you if don't have any.
Date: Sat, 7 Feb 2015 05:56:13 -0800
Subject: [N8VEM-S100:6229] AIRBL 8080a boot loader ROM
I modified the AIRBLv23.asm to include the following as a visual confirmation that I burnt the .OBJ file to EEPROM prior to possible mods in the future.
Unlike the boot from the ROM supplied with the board, this one came up as displayed in this image. Reset / Run appears a bit flaky compared to the delivered ROM. Perhaps there is a timing problem. It's a different menu than the ROM supplied. I was able to push R RAM Test once. It came up with an error. The boot wasn't consistent. Sometimes it appeared to default, without my keyboard entry, to a directory. I replaced the original ROM and the board acted normally, booted cp/m and verified RAM OK.
I simply made the change to the source, built with 'tasm -85 AIRBLv23.asm' in a FreeDOS virtual machine on my Windows 8.1 64bit notebook and burnt the ROM with the resultant .obj file.
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