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 <ard_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Wednesday, June 21, 2000 2:13 PM
Subject: Re: New Finds
> >
> > AM2901APC/7829DP; AM2909PC/7811DP; AM2907PC/7828DM Those are
the
> > bigger chips on the board.
>
> OK, the 2901 is a 4 bit ALU slice (4 bit ALU + 16 4 bit registers).
The
> 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
all
> 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
the
> microinstruction contol an AM2909 sequencer which generates the
addresses
> 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
components
> 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
'special'
> chips (the branch instruction PROM and?), 36 other chips (all look to
be
> 14 or 16 pin), some toggle switches, some pushbutton switches and a
box
> 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
(you'll
> _need_ the data sheet for this!) and the 2909. The PROM sits between
the
> 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