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+++
title = "IMC-2001"
+++
# IMC-2001
This is an old Taiwanese Apple \]\[ / CP/M clone.
# Status
Trying to fix several issues:
- power switch makes some hissing noises
- the lever moving the contacts between 40-character and 80-character
mode for the CRT output is corroded, doesn't always make contact
and produces a flickering image
- keyboard cable is broken, at least the data line
- the paddle and the joystick connectors miss some legs for putting them into
the sockets on the motherboard
- sometimes I get into the monitor
- ~~lower-nibble bit 3 of the key
being pressed is missing, unclear where it is lost, I suspect a
bad register on the motherboard holding the current ASCII value of
the key pressed or something similar~~. Replaced a bad 74LS257N,
works now just fine.
- ROM 1 with BASIC is broken (and gets really hot). This explains
the booting issues.. (will be tricky to get a replacement)
- possibly much more
Known things to work
- The keyboard works electronically (8039 MCS-48 like CPU with a 2K EPROM)
- the Rockwell R6502 CPU has a phase 0 clock and seems to go through
address lines and output data (another strong indicator is the 'Apple \]\['
sign on the monitor when switching on which indicates 6502, 40-character
ROM, video circuit seems to be just fine).
- Monitor is working just fine (which is sort of amazing for such an old
CRT monitor).
- I can boot from a Apple \]\[ CP/M 56k floppy and I get a prompt, now
as the keyboard works and the CP/M on the 80-character card I can also
assume the Z80 is working just fine.
# Images
From the outside:
{{< figure src="/images/hardware/imc-2001/computer_full.jpg" alt="IMC-2001" >}}
Booting into Apple \]\[ CP/M 56k:
{{< figure src="/images/hardware/imc-2001/cpm_40chars.jpg" alt="IMC-2001" >}}
The motherboard and floppy drives:
{{< figure src="/images/hardware/imc-2001/motherboard_internal.jpg" alt="IMC-2001" >}}
Keyboard layout:
{{< figure src="/images/hardware/imc-2001/keyboard_front.jpg" alt="keyboard layout" >}}
Keyboard has a 8039 CPU inside and a 2K EPROM:
{{< figure src="/images/hardware/imc-2001/keyboard_pcb_controller_prom.jpg" alt="PCB and controller" >}}
On the oscilloscope:
{{< figure src="/images/hardware/imc-2001/oscilloscope_serial_keyboard.jpg" alt="serial keyboard signal" >}}
Broken keyboard cable (the black pins are just connectors added by me to test connectivity,
both connector are female per default):
{{< figure src="/images/hardware/imc-2001/keyboard_cable.jpg" alt="PCB and controller" >}}
# Documentation
This is the "Operation Manual for IMC-2001, version 2.01":
{{< figure src="/images/hardware/imc-2001/manual_frontpage.jpg" alt="manual frontpage" >}}
[The complete scanned manual](/hardware/imc-2001/manual_imc_2001_2.01.pdf)
# Schematics
Power connector on the motherboard:
```
O O O O O O
| | | | | +--- GND black
| | | | +----- +12V red
| | | +------- -5V blue
| | +--------- -12V brown
| +----------- +5V white
+------------- +5V white
```
keyboard cable connectors:
connector to machine (sort of a gummy version of a DB-9):
computer has a 9-pin DSUB connector male:
```
+----------- white INTR
| +--------- black GND
| | +------- green DATA
| | | +----- blue RESET
| | | | +--- Yellow CLOCK
-------------
\ O O O O O /
\ O O O O /
---------
| | | +---- red 5V
| | +------ n.c.
| +-------- n.c.
+---------- n.c.
```
On the keyboard PCB there is a strange white connector with the following layout:
```
+------------- white INTR (active low, after last clock tick)
| +----------- black GND
| | +--------- blue RESET (active low)
| | | +------- green DATA
| | | | +----- yellow CLOCK
| | | | | +--- red +5V
+-----------+
|o o o o o o|
+-----------+
| |
```
# Links
* [Mention of the IMC-2001](http://www.epocalc.net/php/liste_models.php?texte=&look=All+fields&yearmax=2018&nocomp=pc&cat=Apple+2+clone):
mentions it on the list of Apple clones
* [Youtube video of similar machine](https://www.youtube.com/watch?v=c7crlJg80Zg):
"APPLE II CLONE + CP/M ------- IMC 2001 made in taiwan.--------", Retro Computacion Argentina Jorge E. Nuviola
|
