Changes
/* Original serial interface (1985) */ Nothing bad about an external PSU!
[[Image:Amstrad RS232.jpg|thumb|right|250px|The Pace RS232 interface, as sold by Amstrad]]
The main difference between the interfaces is that they contain different firmware, and the older one required an external power supply. === Original serial interface (1985) === Amstrad's first serial interface was one of the original peripherals released for the CPC. It was remarkable (in a bad way) for the necessity for an external, brick-like power supply.
Software was supplied on ROM, mostly comprising utility commands for hobbyists rather than a comms application per se - though there was limited terminal emulation for connecting to the then-popular [[Prestel]] service]. The original, UK version included commands for file transfer entitled |SUCK and |BLOW, which used a proprietary Amstrad format similar to [[XModem]]-1k but, annoyingly, subtly incompatible. These commands were reputedly renamed for the US edition to avoid causing offence.
The French company [[M.E.R.C.I.]] sold a custom version of this interface, replacing the original 8k ROM with an 16k Rom adding a [http://en.wikipedia.org/wiki/Minitel minitel] emulator.
Because of the external power supply and the poor quality of the software, this model failed to establish itself as the "standard" serial interface in the way that (say) the [[DDI-1]] did for disc drives. This allowed other serial interfaces to flourish, such as those sold by [[Cirkit]] and [[KDS]].
=== Pace serial interface (1986) ===
As a result, Amstrad dropped their original design and instead chose to remanufacture a [[PacePACE]] design. This included significantly improved hardware (a more compact interface thanks to SMD components and no external PSU) and vastly superior software. However, this redesign also reduced the quality of RS232 signalling by using 0V/5V output voltage instead of -12V/12V.
The software was a ROM version of Pace's the [[Commstar]] terminal utility, from [[CommstarHoneySoft]]. This was a user-friendly program with standard [[XModem]] file transfer functions. However, one foolish design decision was the idea of using a 24x80 screen with a single-line status display - though presenting a good user interface, this forced the use of software rather than hardware scrolling, making the interface unusable for terminal emulation at any speed above 2400 baud. The Amstrad/Pace version was announced on [[:File:ACU8612006.jpg|Amstrad Computer User, Dec 1986, page 6]]. A review occured in Amstrad Computer User, April 1987, pages 46 and 47.
== I/O Ports ==
Here are the I/O Ports (same for original and Pace version): FADCh Amstrad RS323 RS232 [[Z80-DART/Z80-SIO chip|Z8470 (Z80 DART) ]] Channel A Data (R/W) FADDh Amstrad RS323 RS232 [[Z80-DART/Z80-SIO chip|Z8470 (Z80 DART) ]] Channel A Control/Status (R/W) FADEh Amstrad RS323 RS232 [[Z80-DART/Z80-SIO chip|Z8470 (Z80 DART) ]] Channel B Data (R/W) FADFh Amstrad RS323 RS232 [[Z80-DART/Z80-SIO chip|Z8470 (Z80 DART) ]] Channel B Control/Status (R/W) FBDCh Amstrad RS323 RS232 [[8253 chip|8253]] Baudrate Timer 0 Channel A TX Clock (R/W) FBDDh Amstrad RS323 RS232 [[8253 chip|8253]] Baudrate Timer 1 Channel A RX Clock (R/W) FBDEh Amstrad RS323 RS232 [[8253 chip|8253]] Baudrate Timer 2 Channel B RX/TX Clock (R/W) FBDFh Amstrad RS323 RS232 [[8253 chip|8253 ]] Baudrate Timer 0-2 Control Registers (W)
Note: Some interfaces might use a Z80 SIO (which is backwards compatible to the Z80 DART).
Although the Z80-DART (and Z80-SIO) support two channels, most or all existing CPC interfaces seem to use only one channel.
== CP/M ==
The I/O ports are directly supported under CP/M (without needing additional drivers). Like many CP/M functions, the functions are located in the AMSDOS ROM (not on the CP/M disc). These functions are using hardcoded RAM addresses, which conflict with the BASIC memory map, so they can be used only under CP/M, not under BASIC.
== Alternative software ==
The limitations of the [[Commstar ]] software, and the desire to use more recently developed file transfer protocols (such as [[XModem]]-1k, [[YModem]] and [[ZModem]]) meant that many users chose to use their Amstrad serial interface with third-party software. This included:
<gallery caption== 8250 Information "Amstrad's original interface 300dpi scans">Image:Amstrad_RS232C_Top_EN.jpg|Interface Top (probably nonsenseEnglish) ==Image:Amstrad_RS232C_Top_FR.jpg|Interface Top (French)Image:Amstrad_RS232C_PCB_Top.jpg|Interface PCB TopImage:Amstrad_RS232C_PCB_Bottom.jpg|Interface PCB Bottom</gallery>
<gallery caption="Amstrad'''Below is information about the 8250 UART chips newer Pace serial interface">File:Amstrad RS232. As far as known, the jpg|Newer Amstrad Serial /Pace Interface does NOT use that chip, a 8253 yes, but not a 8250File:Amstrad_RS232_Pace_Interface. No idea why that information is herejpg|Pace InterfaceFile:Amstrad_RS232_Pace_PCB_Top.jpg|PCB TopFile:Amstrad_RS232_Pace_PCB_Bottom.jpg|PCB BottomFile:ACU8701002.?'''jpg|Advert (ACU, January 1987)</gallery>
== Manual Reviews ==
<gallery>image:Amstrad_Computer_User8509025.jpg|Review in [[Original Amstrad RS232 interface|Manual of the original RS232 by Amstrad (OCR)Computer User]]image:Amstrad_Computer_User8509026.jpg|image:Amstrad_Computer_User8509027.jpg|image:Amstrad_Computer_User8509028.jpg|</gallery>
== Pictures Manuals == * [[Media:RS232C Serial Interface (Amsoft UK) Manual.pdf|RS232C Serial Interface (Amsoft UK) Manual]] {{EN}} {{PDF}}* [[Media:RS232C Interface Serie (Amsoft FR) Manual.pdf|RS232C Interface Serie (Amsoft FR) Manual]] {{FR}} {{PDF}}* [[Original Amstrad RS232 interface|Manual of the original RS232 by Amstrad (OCR)]]* [[Media:RS232 (Pace) Manual.pdf|RS232 (Pace) Manual]] {{EN}} {{PDF}} == Downloads ==
[[Category:HardwarePeripherals]] [[Category:PeripheralsNetwork]][[Category:Communication Software]] [[Category:Serial_interfaces]][[Category:Amstrad Products]][[Category:Expansion ROM]]
