New Finds

From: John R. Keys Jr. <>
Date: Wed Jun 21 21:34:29 2000

Boy - Thanks for all the information and I have printed it out and
stored it on the zip.
John Keys
----- Original Message -----
From: Tony Duell <>
To: <>
Sent: Wednesday, June 21, 2000 2:13 PM
Subject: Re: New Finds

> >
> > AM2901APC/7829DP; AM2909PC/7811DP; AM2907PC/7828DM Those are
> > bigger chips on the board.
> OK, the 2901 is a 4 bit ALU slice (4 bit ALU + 16 4 bit registers).
> 2909 is a 4 bit control store address sequencer. The 2907 is a bus
> transceiver/latch chip (and is thus uninteresting!).
> I have found a single-page reference to the Am2900 Evaluation And
> Learning Kit in the back of the 2900 databook. According to that :
> 'The system consists of a microprogrammed control unit which controls
> inputs to an AM2901 microprocessor slice. 32 bit microinstructions are
> entered into a RAM in the control unit using the switch register. Each
> microinstruction contains bits to control the AM2901A's A and B
> addtresses, instruction, carry in and data input. Additional bits in
> microinstruction contol an AM2909 sequencer which generates the
> for the microprogram memory. Once entered, microinstructions may be
> executed using a single-step clock or using a pulse generator. The LED
> display provides access to nearly every signal path in the system.
> 16 'Sequence control' instructions are available, including execute,
> branch conditional, jump-to-subroutine, return, and loop. Because this
> set of sequence instructions is implemented in a PROM, the user can
> devise his own set of operations by programming a new PROM.
> The kit is supplied with 40 IC's, all resistors, capacitors, LEDs and
> switches, the PC board and a manual containing assembly instructions,
> theory, and a set of exercises. The user need only solder the
> in place and attach a 5V power supply (2.0A rating)'
> >From the picture of the unassembled kit, there appears to be 1 40 pin
> chip (the 2901), one 28 pin chip (the 2909), a couple of other
> chips (the branch instruction PROM and?), 36 other chips (all look to
> 14 or 16 pin), some toggle switches, some pushbutton switches and a
> of discretes.
> A couple of things may not be too clear from the above description
> (particularly if you don't know the 2900 series). The 'RAM' mentioned
> above is also called the 'control store' or the 'microprogram memory'.
> It's where you store microcode instructions to control the 2901
> _need_ the data sheet for this!) and the 2909. The PROM sits between
> microprogram memory and the 2909 and basically decodes some of the
> microinstruction bits into the 2909 control lines. Which gives you a
> (useful) subset of all the operations the 2909 can perform.
> I hope that's of some help.
> > John Keys
> -tony
Received on Wed Jun 21 2000 - 21:34:29 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:33:02 BST