Thanks for feedback Tom. Will re-look at things. One thing, are you looking at the recent schematic, the RAM pairs and RAM pairs now share the same jumpers (where possible). BTW, slight error (being corrected) on prom sockets to allow 1MX8 UV-EPROMs.
Do you have a schematic for battery backup, good idea BTW.
John Monahan Ph.D
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Tom Lafleur
My first cut on the "new" ver 3 S100 RAM/EPROM board
Make the chip pairs use the SAME configure jumpers
Make both pairs of chips use the SAME pin-out ie; ram or prom in either side, Support RAM on both chip pair.. 28 pin part or larger, this will allow ram or prom to be in lower or higher bank
Remove the jumpers for older and rarely used chips to make the board easy to configure. ie: remove option for chips less that 27C256, or 27C512 (ie: 28pin parts an above)
this will make addressing selection easier..
map address line for RAM using same pins as PROM... ie: no need for matching data sheet, as Ram is not sensitive to address line mix up...
Allow for use of a battery (CR2032) on board to back up RAM as its done on ZetaZ80 with option for external battery option (3 pins... gnd.vbat.gnd) using a DS1210 (allow for two battery sources)
Support for large 39SF040 with a jumper on A18 to select high or low haft of chip, this will allow multi images in prom
Keep small 8 bit boot rom, support 24 and 28 pin devices... allow support of using large chip up to 28C512 with hi/low select of extra address lines... to allow multi images in prom
On Mon, Sep 2, 2013 at 10:08 PM, monahanz <mon...@vitasoft.org> wrote:
[ ]About two years ago Andrew and I made an S-100 bus E-PROM board that could utilize a number or RAM and ROM chips. It proved very popular. All production quality boards were quickly taken. A second "V2" version of the board was later made. That too went quickly.