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Path: utzoo!watmath!clyde!rutgers!cbmvax!fred
From: fred@cbmvax.UUCP
Newsgroups: comp.sys.cbm
Subject: Re: 1750 Memory Expansion
Message-ID: <1095@cbmvax.cbmvax.cbm.UUCP>
Date: Wed, 10-Dec-86 14:46:40 EST
Article-I.D.: cbmvax.1095
Posted: Wed Dec 10 14:46:40 1986
Date-Received: Sun, 14-Dec-86 07:45:02 EST
References: <960001@hplsla.HP.COM>
Organization: Commodore Technology, West Chester, PA
Lines: 34

> I am looking for technical information on the 1750 RAM module.  I have
> seen it advertised locally for $169.  The advertisement said it is
> 512Kbytes in cartridge form for the C64.  I would like to find out what
> the software and hardware interface looks like.
> 
>   Does it use a bank switch technique for addressing 64Kbytes at a time?
>   Or is it 32Kbytes?
>   What address does it use for controlling which bank is active? 

The 1750 RAM module is a 512K byte expansion cartridge for the C128.
The 1700 RAM module is a 128K byte expansion cartridge for the C128.
The 1764 RAM module is a 256K byte expansion cartridge for the C64.

Those diffs aside, they all function alike.  The expansion RAM is not a
contiguous part of the system.  It is accessed via instructions to a DMA
controller located at $DF00 (IO-2) in the c64/128 I/O block.  It features
such operations as Fetch, Stash, Swap, and Compare and a variety of
addressing modes.  The controller will perform these operations at DMA
speed, and can operate on blocks as small as 1 byte or as large as 64K.

The 1764 (for use on C64's) requires a beefier power supply, which is
included.  All modules come with a diskette containing demo programs and
examples.  The 1764 version comes with a RAM DISK utility;  the C128
version of the RAM DISK utility will be finished soon.  The C128 in CP/M
mode already does support the module as a RAM DISK.

Whew.  That should suffice as a brief summary.  Feel free to ask for
details via email.
-- 
Fred Bowen			uucp:	{ihnp4|seismo|caip}!cbmvax!fred
				arpa:	cbmvax!fred@seismo.css.GOV
				tele:	215 431-9100

Commodore Electronics, Ltd.,  1200 Wilson Drive,  West Chester,  PA,  19380