Editing Acorn Electron (section)

====Advanced Plus 3====
[[File:Advanced Plus 3.jpg|thumb|right|250px|The PRES Advanced Plus 3 with a 3½-inch drive]]
Designed and produced by Baildon Electronics and sold by PRES, the Advanced Plus 3 (AP3) was a Plus 1 cartridge interface using the WD1770 controller, supplied with Acorn's ADFS and a single-sided 3½-inch disc drive for £99 plus VAT, offering equivalent functionality to the Acorn Plus 3.<ref name="electronuser198710a">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-01/page/n3/mode/1up | title=PRES announce Advanced Plus 3 | magazine=Electron User | volume=5 | issue=1 | date=October 1987 | access-date=20 January 2021 | page=4 }}</ref> Announced in late 1987, the product was made possible by an agreement between ACP and Acorn to license the ADFS software.<ref name="electronuser198710b">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-01/page/n3/mode/1up | title=Plus 3 upgrade | magazine=Electron User | volume=5 | issue=1 | date=October 1987 | access-date=20 January 2021 | page=5 }}</ref> As with many disc interfaces for the Electron, since the interface provided a connector for the drive, this made it possible to connect a 5¼" floppy disc drive (more common amongst BBC Micro owners) or the more typical 3½-inch drive.

PRES later released a version of ADFS with support for PAGE at &E00, this being achieved by using RAM provided by the Advanced Battery Backed RAM (ABR) cartridge. This version also fixed two notable bugs in Acorn's ADFS, eliminating unreliability when accessing the first tracks on a disc which had previously necessitated the writing of a file (ZYSYSHELP) as a workaround, and switching off the text cursor during disc compaction which had previously caused disc corruption (since the disc data would be processed using screen memory during this operation, and the cursor would modify that data when blinking). The ROM image was supplied on disc for £17.19, whereas a bundle of the ROM image and ABR cartridge was £50.95.<ref name="electronuser198808">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-11/page/n8/mode/1up | title=Improving on perfection | magazine=Electron User | volume=5 | issue=11 | date=August 1988 | access-date=20 January 2021 | last1=Waddilove | first1=Roland | page=9 }}</ref> A separate ADFS version 1.1 product, offered as a 16&nbsp;KB ROM, also provided these bug fixes. Advertised slightly earlier than the E00 ADFS,<ref name="electronuser198712_pres">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-03/page/n3/mode/1up | title=New Product ADFS E00 | magazine=Electron User | date=December 1987 | access-date=14 May 2025 | pages=4 }}</ref> it also replaced the Winchester hard drive support traditionally found in ADFS with "'patches' for future enhancements".<ref name="electronuser198711_pres">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-02/page/n3/mode/1up | title=New Product ADFS Version 1.1 for the Electron | magazine=Electron User | date=November 1987 | access-date=14 May 2025 | pages=4 }}</ref> Such patches, present in both of these ADFS variants, amounted to support for a 256&nbsp;KB RAM disc provided by the company's Advanced Quarter Meg RAM cartridge.<ref name="electronuser198807_pres">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume5/Electron-User-05-10/page/n33/mode/2up | title=PRES | magazine=Electron User | date=July 1988 | access-date=15 May 2025 | pages=34–35 }}</ref>

In 1989, the Advanced Plus 3 Mark 2 was launched, offering a double-sided drive in place of the single-sided drive previously offered. This meant that the storage capacity of each disc was increased from the 320&nbsp;KB of the original Plus 3 to 640&nbsp;KB (this being supported by ADFS on the Master Compact).<ref name="electronuser198905ap3">{{ cite magazine | url=https://archive.org/details/ElectronUserVolume6/Electron-User-06-08/page/n4/mode/1up | title=It's the Plus 3+ | magazine=Electron User | volume=6 | issue=8 | date=May 1989 | access-date=21 January 2021 | page=5 }}</ref>