Difference between revisions of "Schneiderware Pseudo ROM"
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| − | |Address (default | + | |Address (default) || Usage |
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| − | |DFxxh | + | |DFxxh || Schneiderware RAM/EPROM - [[Upper ROM Bank Number|Expansion ROM bank number]] (W)<br>Battery-backed SRAM and/or EPROM are selected when the bank-number matches the jumper-selected values; the memory is then mapped to C000h..FFFFh (in case of READing one must also enable upper ROM via Gate Array). The bank number decoding is a bit strange: |
* EPROM/Read bank: All 8 bits decoded (bank 00h..FFh) | * EPROM/Read bank: All 8 bits decoded (bank 00h..FFh) | ||
* SRAM/Read bank: Only lower 4 bits decoded (bank X0h..XFh) | * SRAM/Read bank: Only lower 4 bits decoded (bank X0h..XFh) | ||
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| + | '''Note''' - Port DFxxh is the standard [[Upper ROM Bank Number]] register, which is also used by AMSDOS, for example. Reserved banks are 00h=Basic, and 07h=AMSDOS. Other bank numbers can be used by one (or more) Schneiderware Pseudo ROM board(s). | ||
== Pictures == | == Pictures == | ||
Revision as of 16:09, 30 September 2010
The Schneiderware Pseudo ROM is a expansion "ROM" board, with 16K EPROM (read-only) and 16K battery-backed SRAM (read/write-able), published by german magazine CPC Schneider International as part of their Schneiderware DIY series. The plain PCB, or the fully assembled board were also available via mail-order.
The ECB Bus connector of the board is intended to be plugged into the Schneiderware Basisplatine, but it could be also wired directly to the CPCs Expansion Port.
Contents
[hide]Software
The magazine article contains three listings with examples how to use the Pseudo ROM board, including a ROM version of the Schneiderware Real Time Clock driver.
Article
- Schneiderware #8 Pseudo ROM (SRAM and EPROM mapped as ROM) (4/1987 pages 26-34, plus corrections in 5/1987 pages 32-34)
I/O Ports
| Address (default) | Usage |
| DFxxh | Schneiderware RAM/EPROM - Expansion ROM bank number (W) Battery-backed SRAM and/or EPROM are selected when the bank-number matches the jumper-selected values; the memory is then mapped to C000h..FFFFh (in case of READing one must also enable upper ROM via Gate Array). The bank number decoding is a bit strange:
The SRAM/Write mode doesn't disable the internal RAM in the CPC, so writes are going both to SRAM and normal RAM at C000-FFFF, that no matter if upper ROM is enabled/disabled via Gate Array; the author recommended to map VRAM to 4000-7FFF via CRTC registers, in order to prevent video dirt during writing. |
Note - Port DFxxh is the standard Upper ROM Bank Number register, which is also used by AMSDOS, for example. Reserved banks are 00h=Basic, and 07h=AMSDOS. Other bank numbers can be used by one (or more) Schneiderware Pseudo ROM board(s).
Pictures
SRAM/EPROM Schematic
