Editing Acorn Archimedes A420

{{Infobox computer
| name         = Acorn Archimedes A420/1
| image        = [[File:Acorn_Archimedes_A420.jpg|250px]]
| caption      = Acorn Archimedes A420/1
| manufacturer = Acorn Computers Ltd
| type         = Personal Computer
| release date = May-July 1989
| discontinued = 1991
| price        = £1,699 (excluding VAT, 1989)
| cpu          = ARM2 @ 8 MHz
| memory       = 2 MB RAM (expandable to 4 MB)
| storage      = 3.5" floppy drive (800 KB), 20 MB ST506 hard drive
| sound        = 8-channel stereo, 8-bit
| os           = RISC OS 2.00
| predecessor  = None (replaced original A400 series)
| successor    = [[Acorn A5000]]
}}

The '''Acorn Archimedes A420/1''' was introduced in 1989 as part of the updated 400/1 series alongside the A410/1 and A440/1. It featured 2 MB RAM as standard and a 20 MB hard drive.

== Overview ==

The A420/1 was introduced in 1989 alongside the A410/1 and A440/1, replacing the earlier 400 series models . The A420/1 was priced at £1,699 excluding VAT . The A420/1 differed from the A410/1 only in having 2MB RAM installed instead of 1MB and included a 20MB ST506 hard disc .

The range consisted of the A410/1 with 1MB RAM and a floppy disc drive, the A420/1 with 2MB RAM, a 20MB ST506 hard disc and floppy disc drive, and the A440/1 with 4MB RAM and a 50MB ST506 hard disc and floppy disc drive .

== Hardware Specifications ==

=== Processor and Architecture ===
The A420/1 was powered by an ARM2 processor  running at 8 MHz, the same as other models in the range.

=== Memory ===
The A420/1 came with 2 MB RAM as standard . The motherboard showed that only the back row of RAM was populated, with the front row having sockets which could be used to upgrade to 4MB .

The A420/1 featured an upgraded MEMC1a memory controller which gave a slight performance improvement over the older systems .

=== Storage ===
The A420/1 included a 20 MB ST506 hard drive  along with a standard 3.5" floppy drive supporting 800 KB capacity.

== Operating System ==

The A420/1 shipped with RISC OS , specifically RISC OS 2.00. Earlier models which shipped with Arthur could be upgraded to RISC OS 2 by replacing the ROM chip containing the operating system .

== Legacy ==

The A420/1 represented the middle tier of the updated Archimedes range, offering a balance between the entry-level A410/1 and the high-end A440/1. With 2 MB RAM standard, it eliminated many of the memory constraints that affected 1 MB systems while remaining more affordable than the 4 MB A440/1.

== See Also ==
* [[Acorn Archimedes A410/1]]
* [[Acorn Archimedes A440/1]]

== External Links ==
* [https://chrisacorns.computinghistory.org.uk/Computers/A4001.html Chris's Acorns: Acorn Archimedes A400/1 series]

[[Category:Acorn Computers]]