https://github.com/codesqueak/compactflashcontroller
An 80-BUS Compact Flash Controller Module
https://github.com/codesqueak/compactflashcontroller
Last synced: 3 months ago
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An 80-BUS Compact Flash Controller Module
- Host: GitHub
- URL: https://github.com/codesqueak/compactflashcontroller
- Owner: codesqueak
- License: other
- Created: 2023-08-14T22:13:57.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2023-12-06T21:22:43.000Z (over 1 year ago)
- Last Synced: 2025-01-22T21:44:35.201Z (5 months ago)
- Size: 1.72 MB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# NAS-GEM-80 Compact Flash Card 1.0
This card is to allow a compact flash module to be used in conjunction with an 80-Bus computer
## Introduction
The board is a standard 8x8 Nascom / Gemini / MAP-80 format card. It features:
1. Port selection with a base between 0x80 and 0xF0
2. 8 bit operation in LBA mode (max 2**28 sectors, approximately 130GB )
3. An aux power connector for adaptors
4. Read / Write and Busy LED's
## Interface - A Brief overview
Addresses are offsets from the base address selected
| Address | Read | Write |
|---------|------|---------------------|
| 0x00 | Data | Data |
| 0x01 | Error Code | Feature Select |
| 0x02 | Sectors to Transfer | Sectors to Transfer |
| 0x03 | LBA 0..7 | LBA 0..7 |
| 0x04 | LBA 8..15 | LBA 8..15 |
| 0x05 | LBA 16..23 | LBA 16..23 |
| 0x06 | LBA 24..27 | LBA 16..23 |
| 0x07 | Status | Write Command |
The following command sequences are sufficient to verify if a card if functional
### Select 8 Bit mode
Addresses are offsets from the base address selected
Write 0x01 to 0x01 - 8 bit mode
Write 0xEF to 0x07 - Set features
### Set Sector Count
Write 0x01 to 0x02 - Transfer one sector
### Select Sector to Read / Write
Write 0x01 to 0x03 - Select address 0x0000001
Write 0x00 to 0x04
Write 0x00 to 0x05
Write 0xE0 to 0x06
### Disable Cache
... otherwise your data won't stick !
Write 0x82 to 0x01 - Disable cache command
Write 0xEF to 0x07 - Set feature
### Read / Write
To read use the command 0x20, to write use the command 0x30 written to 0x07 and then read/write from
the data port 0x00
Between each byte you should check the status port to check if the next byte should be transferred.
However I have found the Z80 at 4MHz to be slow enough not to need this. YMMV
## Other
The CF card timing logic was adapted from a design by Tadeuzd Pycio
Details [Here](http://www.vtsys.pl/interface-compact-flash)
