The Amstrad CSD was a machine that was in-store to demonstrate the hardware of the Amstrad plus.
It had a system cartridge which contained a menu, and could hold a furthur further 12 cartridges.
It has additional hardware to allow switching of cartridges.
Lots of information is not known at this time.
It uses ports fbe0-fbe3. The exact decoding and operation of these ports is unknown.
fbe0 This port is read only it seems. bits 7..4 seem to be related to the dip switches on the CSD with bit 7 seems to be fixed to GND/0v.
bit 6,5 is the timer value. It is the time allowed between choosing next cartridge to play.
bit 6, bit 5
off off = 8 1 1
off on = 16 1 0
on off = 24 0 1
on on = 32 0 0
bit 4 seems to be timer on/off for time limited play.
fbe0 bits 3..0 are defined by the dial
bit 3 is ignored.
bit 6, bit 5
off off = 8s 1 1
off on = 16s 1 0
on off = 24s 0 1
on on = 32s 0 0
bit 4 seems to be timer on/off for time limited play.
bits 3..0 are defined by the dial
bit 3 is ignored.
0 = forever?
1 = 8s,
2 = 56s
fbe2 is read only it seems
bits 7..3 are the currently selected cartridge
bits 3..0 ???
fbe1 is writeable
bits 7,6: ???
bits 5..0: are cartridge number??
fbe3 is writeable:
bits 7..4: are cartridge number
bits 3..0: ???
== The CSD System Cartridge ==
The system cartridge uses the following plus features:
* sprites
* palette
* raster interrupts
The software reads each of the 12 slots to determine if there is a cartridge installed. It also looks for a specific header which can be recreated with the following code:
org &0000
start:
;; a standard cartridge is executed here when inserted into
;; a CPC+.
jp start1 ;; a JP instruction at &0000
defb "AMS" ;; this is the important identification
jp start2 ;; a JP instruction at &0006
jp start3 ;; a JP instruction at &0009
start1:
ld bc,&7f00
out (c),c
ld bc,&7f4f
out (c),c
jp start1
start2:
ld bc,&7f00
out (c),c
ld bc,&7f4b
out (c),c
jp start2
start3:
ld bc,&7f00
out (c),c
ld bc,&7f40
out (c),c
jp start3
end start
Offset 0 is the normal execution point for cartridges when run on GX4000 and Plus.
It is believed the others are for a rolling demonstration mode, and a play mode that is limited.
The only cartridge to have this header is [[Pang (cartridge)|Pang]].
== Pictures ==
<gallery caption="Some photos of Amstrad Expo 90">
Image:csdscreen1.jpg
Image:csdscreen2.jpg
Image:csdface.jpg
Image:csddaughter.jpg
</gallery>
== Download ==
* [[Media:CSD Jukebox.cpr]] (JukeBox Cartridge .CPR file)
fbe2 is read only it seems
bits 7..3 are the currently selected cartridge
bits 3..0 ???
fbe1 is writeable bits 7,6: ???bits 5Courtesy of Amstrad.cpc.0: are cartridge number??free.fr
fbe3 is writeable[[Category:bits 7..4Hardware]][[Category: are cartridge numberbits 3..0CPC Plus]][[Category: ???Amstrad Products]][[Category:Cartridges]][[Category:Expansion ROM]]