Green 753

Green 753

Green 753

If anyone knows how to modify a Phoenix BIOS program and can successfully raise the Green 753 maximum memory from 40 MB to 72 MB's -- I will offer a brand new Barebone Green 753 in exchange for rights to the updated BIOS

The Green 753 was sold by ARM, Brick/Egro, Trogon and Jetta -- perhaps a dozen more brands. The Green 753 and Green 753+ are two closely related laptops and share the same case and they also use the same batteries, but they have different motherboards that require different daughter boards.

The last version of the factory BIOS could only reported CPU speeds only up to 166 MHz. I have installed a 200 MHz CPU and it operates correctly in the Green but the BIOS do NOT report the correct CPU speed - the CPU does run at 200 MHz per Sandra test program. No AMD CPU's will operate in the Green 753 because of the BIOS - there's no attempt to displace a POST screen. I also tried a Cyrix MII and never got it to POST.

The 753 came with all of the following: 11.3" TFT, 11.8" TFT, 12.1" TFT or 11.3" & 12.1" dual scan LCD's. The dual scan LCD's are not as bad as some of the ones found on Chicony or Mitac laptops, but the active matrix (TFT) is still the best LCD. Interestingly, and LCD lid can be swapped out with any of the other lids as long as it's done as a complete assembly.

Note: The LCD adapter board (which also has the On/Off switch onboard) is different in the 753 and so will not swap with a 753+ adapter board. Again a different motherboard required different daughter boards.

Many 753's have only 1MB of video RAM, however a second 1 MB can be plugged into sockets on the bottom side of the motherboard. To fill the sockets you must completely disassemble the 753, so it's not an easy task for the faint hearted.

The 753 power adaptor has a four pin connector power supply and is rated at 22 - 18 volts - a strange rating that means that the voltage goes down as the current goes up.

The 753 uses only 72 pin Fast Page memory modules and has 8 MB of RAM on the motherboard. The maximum that memory can be expanded to is only 40 MB in the machines that I've upgraded. The Chicony MP968 uses the same Fast Page memory and many of those machines also won't register 72 MB. One of the companies that sold the 753 lists in their specifications that they supplied it with up to 72MB, so I need to see how this was possible. (Maybe with some unknown BIOS update?)

The hard drive carrier module plugs into the side of the 753 and is the same as the 753+. The largest hard drive that I've installed in a 753, so far, is a 5 GB drive.

I've heard from a reliable source that if a hard drive larger than 8.3 GB is installed that the CD-ROM drive will not function correctly - some BIOS or circuit problem exists!

While there isn't any USB port in the Green 753, all other of the normally expected ports are there including an infrared port.

The PCMCIA slots do not support Cardbus devices, but there is a Zoom video PCMCIA slot and a TV out port. The slots are 16 bit only and so your PCMCIA cards must work with 16 bit slots and not just 32 bit slots.

The 753 has a BIOS that allows much more customization of boot device and other features that is not found in the Chicony MP975 BIOS. The 753 more closely matches the Chicony MP968/ARa laptops for features, but the 753 comes out ahead with it's built-in floppy and CD drives. This is a real plus if you need to use both drives while on the road or while loading the operating system from a CD.

I have a small supply of original batteries, but that does not mean that the old ones should thrown away - the plastic battery case can be opened and new cells can be installed. Replacement batteries for these machines are VERY hard to find, so DO NOT throw away your old battery, have them rebuilt. If you have any unwanted batteries, please send them to me for a credit.

Here's an old price list from the "good" old days

Last Price update 02-01-97

Model Number	Description	Price
TS753CD-120D	P/120 MHz, 11.3" Dstn, 1.08Gb, 16Mb	$1899 ($68/month)*
TS753CD-133D	P/133 MHz, 11.3" DSTN, 1.3GB, 24 MB	$2099 ($74/month)*
TS753CD-120T	P/120 MHz, 11.3" Active, 1.0MB, 16MB	$2399 ($84/month)*
TS753CD-133T	P/133 MHz, 12.1"Active, 1.3GB, 16Mb	$2799 ($98/month)*
TS753CD-150T	P/150 MHz, 12.1"Active, 2.1GB, 24 MB	$3099 ($104/month)*
TS753CD-166TX	P/166 MHz, 12.1"Active, 2.1GB, 40 MB 33.6 Fax Modem	$3399 ($129/month)*

(The above prices are for reference and are not today's selling prices)

Motherboard Switch settings for Green 753

Do not use with a Green 753+

Always record the old switch settings before changing them - just in case!

CPU Speed Settings

Note: It is possible to overclock any Pentium CPU by changing the SW1 settings to a higher speed setting. This may not be a stable condition and the CPU and/or motherboard may be damaged. Data may be lost or corrupted also. Proceed at your own risk when overclocking a CPU.

Speed	SW1-1	SW1-2	SW1-3	SW1-4
75	OFF	OFF	OFF	OFF
90	OFF	ON	OFF	OFF
100	ON	ON	OFF	OFF
120	OFF	ON	OFF	ON
133	ON	ON	OFF	ON
150	OFF	OFF	ON	OFF
150	OFF	ON	ON	ON
166	ON	ON	ON	ON
200*	ON	ON	ON	OFF
233**	?	?	?	?

* The above 200 MHz setting is correct, but the BIOS does not report the 200 MHz speed - it reports the CPU running at 166 MHz with most BIOS versions.

**If you have installed a 233 or an AMD CPU in this machine please Emil the switch settings and details to me!

SW-2

SW2-1	SW2-2	SW2-3	SW2-4	SW2-5	SW2-6	SW2-7	SW2-8
ON	ON	ON	ON	ON	ON	OFF	OFF

I believe that this is correct for all 753's - don't mess with your SW2 switch settings!!!!!!

CPU Core Voltage Settings

Voltage	SW3-1	SW3-2	SW3-3	SW3-4
2.9	ON	ON	OFF	OFF
3.1	ON	OFF	OFF	OFF
3.3	OFF	OFF	ON	OFF

*2.9v Vcc should be okay for MMX CPU's

3.3v is the correct Vcc for most non-mmx CPU's