[[boards:sbc:cpu280:start]]
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boards:sbc:cpu280:start [2019/09/16 01:55] – Revision from 2019-09-16 boards:sbc:cpu280:start [2026/06/15 12:31] (current) – external edit 127.0.0.1
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 /* Imported from Wayback Machine /* Imported from Wayback Machine
    Original URL : https://retrobrewcomputers.org/doku.php?id=boards:sbc:cpu280:start    Original URL : https://retrobrewcomputers.org/doku.php?id=boards:sbc:cpu280:start
-   Snapshot date: 2019-09-16+   Snapshot date: 2025-11-17
    Generator    : wayback-archiver    Generator    : wayback-archiver
 */ */
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 Please use this space to add any notes/comments on this board that don't fit into the above sections. (Periodically, these comments may be re-arranged to be better incorporated into a new revision of the wiki page.) Please sign your comments using the wiki “Insert Signature” feature! — //[[mailto:admin@retrobrewcomputers.org|Andrew Bingham]] 2016/02/27 13:01// Please use this space to add any notes/comments on this board that don't fit into the above sections. (Periodically, these comments may be re-arranged to be better incorporated into a new revision of the wiki page.) Please sign your comments using the wiki “Insert Signature” feature! — //[[mailto:admin@retrobrewcomputers.org|Andrew Bingham]] 2016/02/27 13:01//
 +
 +===== Notes from Richard Edwards =====
  
 The following are notes from my build — //[[mailto:rbc@trick-1.net|Richard Edwards]] 2019/08/10 16:32//— The following are notes from my build — //[[mailto:rbc@trick-1.net|Richard Edwards]] 2019/08/10 16:32//—
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 <code code> <code code>
     actual values:\\     actual values:\\
-    A: 5.25" DD, 80 tracks, double-sided\\ +A: 5.25" DD, 80 tracks, double-sided\\ 
-    B: 5.25" DD, 80 tracks, double-sided\\ +B: 5.25" DD, 80 tracks, double-sided\\ 
-    C: ---\\ +C: ---\\ 
-    D: ---+D: ---
 </code> </code>
  
 <code code> <code code>
-    1. Drive A:\\ +    1. Drive A: 
-    2. Drive B:\\ +2. Drive B: 
-    3. Drive C:\\ +3. Drive C: 
-    4. Drive D:\\ +4. Drive D: 
-    0. back\\ +0. \back 
-    --> 1\\ +--> \1 
-            0. no drive\\ +0. no \drive 
-            1. 3.5" DD\\ +1. 3.5" \DD 
-            2. 3.5" HD\\ +2. 3.5" \HD 
-            3. 8"\\ +3. 8" 
-            4. 5.25" HD 360\\ +4. 5.25" HD \360 
-            5. 5.25" DD\\ +5. 5.25" \DD 
-            6. 5.25" HD 300/360\\ +6. 5.25" HD 300/\360 
-            --> 2\\ +--> \2 
-            0. 40 tracks\\ +0. 40 \tracks 
-            1. 80 tracks\\ +1. 80 \tracks 
-            --> 1\\ +--> \1 
-            0. single sided\\ +0. single \sided 
-            1. double sided\\ +1. double \sided 
-            --> 1+--> 1
 </code> </code>
  
 <code code> <code code>
-    actual values:\\ +    actual values: 
-    A: 3.5" HD, 80 tracks, double-sided\\ +A: 3.5" HD, 80 tracks, double-\sided 
-    B: 5.25" DD, 80 tracks, double-sided\\ +B: 5.25" DD, 80 tracks, double-\sided 
-    C: ---\\ +C: --- 
-    D: ---+D: ---
 </code> </code>
  
 <code code> <code code>
-    1. Drive A:\\ +    1. Drive A: 
-    2. Drive B:\\ +2. Drive B: 
-    3. Drive C:\\ +3. Drive C: 
-    4. Drive D:\\ +4. Drive D: 
-    0. back\\ +0. \back 
-    --> 2\\ +--> \2 
-            0. no drive\\ +0. no \drive 
-            1. 3.5" DD\\ +1. 3.5" \DD 
-            2. 3.5" HD\\ +2. 3.5" \HD 
-            3. 8"\\ +3. 8" 
-            4. 5.25" HD 360\\ +4. 5.25" HD \360 
-            5. 5.25" DD\\ +5. 5.25" \DD 
-            6. 5.25" HD 300/360\\ +6. 5.25" HD 300/\360 
-            --> 2\\ +--> \2 
-            0. 40 tracks\\ +0. 40 \tracks 
-            1. 80 tracks\\ +1. 80 \tracks 
-            --> 1\\ +--> \1 
-            0. single sided\\ +0. single \sided 
-            1. double sided\\ +1. double \sided 
-            --> 1+--> 1
 </code> </code>
  
 <code code> <code code>
-    actual values:\\ +    actual values: 
-    A: 3.5" HD, 80 tracks, double-sided\\ +A: 3.5" HD, 80 tracks, double-\sided 
-    B: 3.5" HD, 80 tracks, double-sided\\ +B: 3.5" HD, 80 tracks, double-\sided 
-    C: ---\\ +C: --- 
-    D: ---+D: ---
 </code> </code>
  
 <code code> <code code>
-    1. Drive A:\\ +    1. Drive A: 
-    2. Drive B:\\ +2. Drive B: 
-    3. Drive C:\\ +3. Drive C: 
-    4. Drive D:\\ +4. Drive D: 
-    0. back\\ +0. \back 
-    --> 0+--> 0
 </code> </code>
  
-1. Disk Drives\\ +1. Disk \Drives 2. \Interfaces 3. \Other 0. Exit (Reboot) –> 3
-2. Interfaces\\ +
-3. Other\\ +
-0. Exit (Reboot)\\ +
-–> 3+
  
 <code code> <code code>
-    actual values:\\ +    actual values: 
-    Memory 0k, Daylight Saving disabled, Boot A:, Chain *+Memory 0k, Daylight Saving disabled, Boot A:, Chain *
 </code> </code>
  
 <code code> <code code>
-    1. Memory Size\\ +    1. Memory \Size 
-    2. Daylight Saving\\ +2. Daylight \Saving 
-    3. Boot Drive\\ +3. Boot \Drive 
-    4. Drive Search Chain\\ +4. Drive Search \Chain 
-    0. back\\ +0. \back 
-    --> 1\\ +--> \1 
-            Memory: 0=512k, 1=1M, 2=2M, 3=4M --> 3+Memory: 0=512k, 1=1M, 2=2M, 3=4M --> 3
 </code> </code>
  
 <code code> <code code>
-    actual values:\\ +    actual values: 
-    Memory 4096k, Daylight Saving disabled, Boot A:, Chain *+Memory 4096k, Daylight Saving disabled, Boot A:, Chain *
 </code> </code>
  
 <code code> <code code>
-    1. Memory Size\\ +    1. Memory \Size 
-    2. Daylight Saving\\ +2. Daylight \Saving 
-    3. Boot Drive\\ +3. Boot \Drive 
-    4. Drive Search Chain\\ +4. Drive Search \Chain 
-    0. back\\ +0. \back 
-    --> 3\\ +--> \3 
-            Boot Drive: A..P (Q=EPROM) --> Q+Boot Drive: A..P (Q=EPROM) --> Q
 </code> </code>
  
 <code code> <code code>
-    actual values:\\ +    actual values: 
-    Memory 4096k, Daylight Saving disabled, Boot Q:, Chain *+Memory 4096k, Daylight Saving disabled, Boot Q:, Chain *
 </code> </code>
  
 <code code> <code code>
-    1. Memory Size\\ +    1. Memory \Size 
-    2. Daylight Saving\\ +2. Daylight \Saving 
-    3. Boot Drive\\ +3. Boot \Drive 
-    4. Drive Search Chain\\ +4. Drive Search \Chain 
-    0. back\\ +0. \back 
-    --> 0+--> 0
 </code> </code>
  
-1. Disk Drives\\ +1. Disk \Drives 2. \Interfaces 3. \Other 0. Exit (Reboot) **Sample Boot Output**
-2. Interfaces\\ +
-3. Other\\ +
-0. Exit (Reboot)\\ +
-**Sample Boot Output**+
  
 This is what I get on the console when it boots. I used setup to set my boot drive to Q which is the EPROM. This is what I get on the console when it boots. I used setup to set my boot drive to Q which is the EPROM.
  
-CPU280 Boot Loader V1.2 RBC 8-Mar-2017\\ +CPU280 Boot Loader V1.2 RBC 8-Mar-\2017 http://www.retrobrewcomputers.org based on Cold Loader Program V1.13 TR \950314 Press DEL to run SETUP. 2048k RAM ok
-http://www.retrobrewcomputers.org\\ +
-based on Cold Loader Program V1.13 TR 950314\\ +
-Press DEL to run SETUP.\\ +
-2048k RAM ok+
  
-CP/M-3 Loader V1.2 RBC 8-Mar-2017\\ +CP/M-3 Loader V1.2 RBC 8-Mar-\2017 based on CP/M-3 Loader V1.\13 Booting system file from EPROM
-based on CP/M-3 Loader V1.13\\ +
-Booting system file from EPROM+
  
-BNKBIOS3 SPR FE00 0200\\ +BNKBIOS3 SPR FE00 \0200 BNKBIOS3 SPR D000 \2000 RESBDOS3 SPR F800 \0600 BNKBDOS3 SPR A200 2E00
-BNKBIOS3 SPR D000 2000\\ +
-RESBDOS3 SPR F800 0600\\ +
-BNKBDOS3 SPR A200 2E00+
  
 62K TPA 62K TPA
  
-CP/M-3 BIOS V1.2 RBC 8-Mar-2017\\ +CP/M-3 BIOS V1.2 RBC 8-Mar-\2017 http://www.retrobrewcomputers.org based on CP/M-3 BIOS V1.13 TR 950314
-http://www.retrobrewcomputers.org\\ +
-based on CP/M-3 BIOS V1.13 TR 950314+
  
 E: MDrive 3840k E: MDrive 3840k
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 happy building — //[[mailto:rbc@trick-1.net|Richard Edwards]] 2019/08/10 16:40//— happy building — //[[mailto:rbc@trick-1.net|Richard Edwards]] 2019/08/10 16:40//—
 +
 +\\
 +
 +===== Notes from Will Sowerbutts =====
 +
 +**Reh CPU-280 Board:**
 +
 +I fitted a pair of W27C512 EEPROMs instead of UV EPROMs, they can be quickly programmed with the common MiniPro TL866 programmers.
 +
 +From reading the BOM, I was confused which two of the CK1-CK27 caps were the 10uF tantalums. They are CK1 and CK9.
 +
 +You need to fit an insulator under the crystals in order to prevent them shorting out on PCB vias. I 3D printed a small shim to do the job.
 +
 +The manual says that J5 (EEPROM type select) is pre-connected to suit 27C256 ROMs. This was not the case on my PCB. A 3-pin header and jumper is required at J5.
 +
 +CN3 is a 20-pin connector with two RS232 ports on it. One might think you can just split the 20-way ribbon cable and connect each 10-pin strip to an IDC DB9, however this will not work as the pinout is wrong. You have to use the pin mapping that Richard describes above.
 +
 +The 9.6MHz oscillator at Q3 is not required if you're using only standard PC 3.5” floppy drives.
 +
 +I found 15ns ATF16V8B PLDs worked well in my CPU-280.
 +
 +See the note below about using 74LS parts for IC6, IC7 and IC8.
 +
 +The CPU-280 manual says to measure the CAS pulse width and adjust the value of C6 to get the CAS pulse width to 20ns. [[421|Page 22 of this document]] shows a timing diagram. You need to inspect the width of the positive pulses on one of the /CAS lines during a burst memory access, as shown in the third diagram, “Burst-Speicherzugriffe (RAM)”. To test this I probed pin 17 on the Z280CAS4 GAL (/CAS for DRAM ICs 11 and 12) while MBASIC.COM ran an infinite loop (something to keep the CPU busy that wouldn't fit in cache).\\
 +[[https://www.retrobrewcomputers.org/lib/exe/fetch.php?tok=d01303&media=https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/boards/sbc/cpu280/cpu280-burstmode-cas.jpg|{{https://www.retrobrewcomputers.org/lib/plugins/ckgedit/fckeditor/userfiles/image/boards/sbc/cpu280/cpu280-burstmode-cas.jpg?500x375|www.retrobrewcomputers.org_lib_plugins_ckgedit_fckeditor_userfiles_image_boards_sbc_cpu280_cpu280-burstmode-cas.jpg}}]]
 +
 +**Reh ECB-IDE Board:**
 +
 +Watch out for the orientation of RN4, RN5, RN6 – Pin 1 is not in the same orientation on each network.
 +
 +There isn't enough space around D2, D3, D4, D5 to fit them all even using 3mm LEDs. I don't use -5V, -12V or +12V so I fitted only D3 (+5V) and D1 (IDE activity).
 +
 +To set up the active terminator, you need to adjust P1 until you get around 2.7V on pin 1 of the bus termination resistor networks (RN4, RN5, RN6).
 +
 +You do not need to fit R6, R7, R8, R9 if you are using this board with CPU-280.
 +
 +See the note below about using 74LS parts for IC2 and IC3.
 +
 +You need to fit a jumper across pins 1-2 (pins closest to parallel port connector) on SW1 and SW2 otherwise /RESET or /NMI will be constantly asserted.
 +
 +You also need a jumper at J1 to select the reset style (if using with CPU-280, jumper the two pins closest to the centre of the board).
 +
 +**Part Substitution:**
 +
 +I found that the ECB-IDE board used with CPU-280 would give occasional but reproducible disk errors when reading from the IDE drive (using a Compact Flash card). Changing to a different CF card made no difference.
 +
 +The issue went away when the 74ACT245 at either REH-IDE IC3 or CPU-280 IC7 (or both) were substituted with 74LS245 or 74AHCT245 (other logic families may also work, these are the two I tested with successfully).
 +
 +74LS244 and 74LS245 have hysteresis at the bus inputs to improve noise margins. I have therefore installed 74LS on all bus transceivers:
 +
 +CPU-280 IC6, IC8 and REH-IDE IC2 are substituted with 74LS244
 +
 +CPU-280 IC7 and REH-IDE IC3 are substituted with 74LS245
 +
 +**Connecting PC floppy drives:**
 +
 +To connect PC floppy drives to the CPU-280, I soldered a shrouded 34-pin header to the last 34 pins of CN2, pins 17-50. These are the 34 pins closest to the RTC chip, and pin 1 on the header should be pin 17 on CN2. The pinout is not directly compatible with PC floppy drives, so I made up an adapter board to convert this to a standard PC floppy cable. The adapter has two 34-pin headers: An input which connects to the CPU-280 with a straight through cable, and an output which connects to a standard PC floppy cable with two drives which the CPU-280 sees as A: (before the twist) and B: (after the twist). On the output header I removed pin 3, which was blocked as a keying pin on several of the standard PC floppy cables I have.
 +
 +^CPU-280 CN2 pin     ^Adapter 34-pin input^Adapter 34-pin output^Signal Name                    ^
 +|1-16                |n/c                 |n/c                  |No Connect - Unused pins on CN2|
 +|18                  |2                   |n/c                  |RWC/RPM                        |
 +|20                  |4                   |2                    |HDLD/DENSITY                   |
 +|22                  |6                   |n/c                  |DS3                            |
 +|24                  |8                   |8                    |INDEX                          |
 +|26                  |10                  |12                   |DS0/DSB                        |
 +|28                  |12                  |14                   |DS1/DSA                        |
 +|30                  |14                  |n/c                  |DS2                            |
 +|32                  |16                  |10 and 16            |MOTOR ON                       |
 +|34                  |18                  |18                   |DIRECTION                      |
 +|36                  |20                  |20                   |STEP                           |
 +|38                  |22                  |22                   |WRITE DATA                     |
 +|40                  |24                  |24                   |WRITE GATE                     |
 +|42                  |26                  |26                   |TRACK 0                        |
 +|44                  |28                  |28                   |WRITE PROTECT                  |
 +|46                  |30                  |30                   |READ DATA                      |
 +|48                  |32                  |32                   |SIDE/HEAD SELECT               |
 +|50                  |34                  |34                   |DISK CHANGE                    |
 +|17-49 (All odd pins)|1-33 (All odd pins) |1-33 (All odd pins)  |GROUND                         |
 +
 +— //[[mailto:will@sowerbutts.com|Will Sowerbutts]] 2021/03/14 21:11//—
  
 \\ \\
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 ===== Photo Gallery ===== ===== Photo Gallery =====
  
-Nothing was found.+No images found.
  
 ===== File List ===== ===== File List =====
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 1.5 MiB 1.5 MiB
 2019/08/10 02:28 2019/08/10 02:28
 +[[https://retrobrewcomputers.org/lib/exe/fetch.php?media=boards:sbc:cpu280:cpu280-burstmode-cas.jpg|cpu280-burstmode-cas.jpg]]
 +2.2 MiB
 +2021/03/14 17:11
 [[https://retrobrewcomputers.org/lib/exe/fetch.php?media=boards:sbc:cpu280:cpu280-eagle.zip|cpu280-eagle.zip]] [[https://retrobrewcomputers.org/lib/exe/fetch.php?media=boards:sbc:cpu280:cpu280-eagle.zip|cpu280-eagle.zip]]
 61.9 KiB 61.9 KiB
boards/sbc/cpu280/start.1568598957.txt.gz · Last modified: (external edit)
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