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Indus Ramcharger Help


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thanks for the photos

lol i can see how you got around the tight-fit issues - love the resourcefulness :) (proper modding!)

here are the photos of mine. the problem i had was the right angled pin header had to go on the opposite side in order to close the casing. so i just removed all my wires and left it ready to tackle at a later date.

i'll have a go this week





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thanks for the photos

lol i can see how you got around the tight-fit issues - love the resourcefulness :) (proper modding!)

here are the photos of mine. the problem i had was the right angled pin header had to go on the opposite side in order to close the casing. so i just removed all my wires and left it ready to tackle at a later date.

i'll have a go this week


Where did you find that header? I haven't run across one yet. All I have found is males... :/

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A member here sold boards a couple of years ago. I got one and it fit without cable. I‘ll try to post a picture ASAP. Unfortunately he doesn‘t seem to be around any more.



Gesendet von iPhone mit Tapatalk

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Announcing production run of Indus Ramchargers!


(just kidding!) :grin:

(they're actually amiga 256mb boards - https://www.cameramiga.com/product-page/mister-fpga-memory-vertical-version-module- but they sure reminded me of xrbrevin's breadboard!)

Sorry for my dreaming out loud. Sign me up if it ever happens :)


dammit! you had me going there for a second :-o

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  • 2 weeks later...

Would have been nice to get on board with that run way back. Looks like tregare hasn't logged into AA since 2015.


Last year I acquired my first Indus drive to see what all the fuss was about. Initial impression was they mostly seem to me like a fussy US doubler that only works in highspeed mode with a special DOS XL, or SpartaDOS X. From what I've read about the RAMcharger, aside from the CP/M capability, it could do a full highspeed track buffer. And at 70+K, it should be faster or than, or at least on par with Happy or maybe even Speedy in highspeed mode.

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I worked on a CP/M implementation for the Indus drive with the ramcharger that expands the memory to 64K. I don't know what changes Indus made to the released version as I wasn't even aware that they had released it or even the ramcharger. After the terminal program is loaded, insert the CP/M disk and press "drive" and "error" buttons at the same time to boot from floppy disk. In 40 character mode, the terminal will auto-scroll left and right (I don't recall if there was a way to force the screen to shift left or right other than it followed the cursor). The 80 character mode is a 3x5 font, barely readable, but it works. Although it's slow, the monitor program will allow CP/M to operate with a second floppy, which doesn't have to be an Indus drive. The data path is Indus <-> Atari (monitor program) <-> other floppy drive.


There was also a bootable "doubler" program for a standard Indus drive (no ramcharger needed), that switches to Indus to be compatible with the 1050's "doubler" mode (19 microseconds per bit which is about 52.6 kilo-baud) . I don't know if Indus released this or not. Again, you press "drive" + "error" buttons at the same time to boot this floppy. After that the Indus will be "double" compatible. I have a copy of this "double" floppy that is still working, but I don't know how to duplicate it. I need someway to format and image copy a 5.25" floppy (only need the first 16 sectors or so to be copied). I have a working Atari 400 and also a 130XE, and the 130XE can boot into Spartdos 2.3, so I may be able to image copy the floppy.


If I recall correctly, the Atari floppy disk drives spin at 300 rpm instead of 360 rpm. This is an issue if using an ATR 8000 as an Atari 8 bit disk drive interface. You'll need to adjust the speed on a 5.25" floppy drive down to 300 rpm in order to make the drives "compatible" with Atari drives. I recall a program that I think ran on the Atari (might have been the ATR) that displayed the rpm as you adjusted the speed. All of my ATR stuff is in storage and I don't know if it works.

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I found a copy of the instructions.




This document explains the specifics of your Indus GT based CPM

2.2 system. The CPM system runs in the Indus GT disk drive,

which contains a Z80 microprocessor, and 64K of ram (thanks to

the ram charger). The Indus drive in turn, communicates with

your Atari computer. Most of the time, the Atari computer acts

as a terminal, but is also used to send data to the printer, and

also to operate a second disk drive. The basic nature of this

environment is that the Indus is the boss, and the Atari is the

slave processor in a network based system.




Indus GT disk drive with 64K ramcharger board, configured as

drive 1; an Atari home computer with at least 48K. Optionally a

second double density capable drive, and an Atari compatable

printer (or 850 interface connected to a printer).


Boot up:

Insert the terminal disk into the Indus drive and boot the Atari

(with Basic disabled if an XL or XE type computer). You will see

a menu "A: TRM40", and "B: TRM80". TRM40 is a 40 column terminal

program suitable for TV's, TRM80 is an 80 column usually

requiring some type of monitor. Press the "A" key for TRM40 or

"B" for TRM80.


After the terminal program has been booted, insert the CPM disk

into the Indus and while holding down the "drive type" button,

press the "error" button; this will boot up CPM, which will ask

you to hit the return key to continue. At this point your are

booted up and running CPM.


Terminal emulation


TRM40 emulates an ADM-31, and TRM80 emulates an ADM3A.

TRM40 control keys: ^bk sp - screen toggle

^3 - cursor display lock/unlock

^; - left shift screen

^. - right shift screen


Second disk option


A second drive may be used with CPM, this will be slow as data

must pass thru the Atari computer. To use drive "2" as double

density, specify CPM disk "B:". To use drive "2" as single

density, specify CPM disk "C:". When transferring CPM files from

a double density disk to another double density disk, it is

faster if the destination disk is put in drive "1" (CPM "A:") and

the source disk in drive "2" (CPM "B:"). Note drive "1" must

always be used as a double density disk. Only drive "2" can be

access as a single density drive (as CPM disk "C:").


Printer option


Any standard Atari printer (or printer hooked up via an Atari 850

interface) can be accessed using the standard CPM conventions.



This was the CPM procedure used to install all of the Digital

Research patches for CPM 2.2, and to create EXSUB.COM. EXSUB is

used to get out of XSUB state (refer to the CPM manual).



INIT is used to initialize a floppy disk for Indus CPM. Init can

format a disk, generate a bootable disk, and optionally erase a

directory. Run the "INIT" program and remove your main disk,

insert a fresh disk, and reply to the prompts as asked. You can

optionally format a disk, and optionally erase the directory.

INIT always will copy the boot information, creating a bootable




ICDS is used to copy files to/from an Atari DOS compatable

diskette. The Atari DOS diskette must be a double density (256

byte sectors) disk, such as XLDOS or MYDOS. ICDS is similar to

Atari DOS, with the addition that CPM disks are supported. Run

ICDS from drive "1" (CPM disk "A:") and place the Atari DOS disk

in drive "2". To specify a CPM file, prefix the file name with

"A:", to specify a DOS file prefix the name with "2:". The

following commands can be used:


A - display a directory (specify "A:", or "2:")

C - copy a file (or files, wild cards supported)

D - delete a file

H - display help menu

When transferring a file from Atari format to CPM format, or vice

versa, you will be asked for text file translation, answer yes if

the file is a text file. The conversion mainly involes

converting the Atari end-of-line character into a CPM carriage

return-line feed sequence (or vice versa).

As an example, the following would be entered after a "C" command

to copy an Atari file named "TEST.TXT" to a CPM file of the same




In this example, text translation would be desired (enter "Y").

Note: MYDOS style subdirectories are supported with ICDS.


The following tables describe the structures of the double

density and single density disks used by Indus CPM. These tables

are the disk parameter blocks used by CPM to organize the data on

a disk. This information should be used to configure "alien"

disk programs available on other non-Indus based CPM systems to

transfer data to an Indus compatible CPM disk.


Double density: 40 tracks, 18 256-byte sectors per track


DB 3,7,0 ;1K AU PARAMS

DW 170 ;171*1K=171K DISK SIZE





; interleave = 1


Single density: 40 tracks, 18 128-bytes sectors per track


DB 3,7,0 ;1K AU PARAMS






; ;interleave = 5

DB 01,06,11,16

DB 03,08,13,18

DB 05,10,15

DB 02,07,12,17

DB 04,09,14

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Forgot to mention, some control key sequences for the 40 character terminal, using ^ to represent control key:


^ delete - toggles screen between left and right side

^ ; - scrolls screen left one character

^ . - scrolls screen right one character

^ 3 - "locks" screen in place (not sure on this one)

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  • 1 year later...

What are folks running with CP/M on their Ataris?  I'm waiting for my SRAM Charger and I'm doing lots of research based on these old threads, but what is the best-in-class type of stuff that you can use? Even just for nostalgia, beyond text adventure games (which I love), I'm unlikely to run anything more than just to play around with it. Anyone try Muliplan or Supercalc?

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1 hour ago, slx said:

Can the Indus GT with RAMCharger read other systems‘ CP/M floppies like the C128/1571 or does it need software converted for Atari-CP/M?


As far as I know, every CP/M implementation has proprietary disk geometry (number of tracks, number of sectors per track, physical sector size and such) and additionally the file system parameters like the number of reserved tracks, directory size, block (= cluster) size, software interleave etc. are left to the discretion of the CP/M BIOS. So data exchange via floppies between different CP/M implementations may be problematic, unless the BIOS/floppy combo allows to tune the parameters and set them as that different system requires. I may be wrong, but I do not think the Indus CP/M BIOS is very flexible in this.

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